diff --git a/src/if_py_both.h b/src/if_py_both.h
index 4662504..e11c62e 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -29,9 +29,25 @@
 #define PyErr_SET_STRING(exc, str) PyErr_SetString(exc, _(str))
 #define PyErr_SetVim(str) PyErr_SetString(VimError, str)
 #define PyErr_SET_VIM(str) PyErr_SET_STRING(VimError, str)
+#define PyErr_FORMAT(exc, str, tail) PyErr_Format(exc, _(str), tail)
+#define PyErr_VIM_FORMAT(str, tail) PyErr_FORMAT(VimError, str, tail)
+
+#define Py_TYPE_NAME(obj) (obj->ob_type->tp_name == NULL \
+	? "(NULL)" \
+	: obj->ob_type->tp_name)
 
 #define RAISE_NO_EMPTY_KEYS PyErr_SET_STRING(PyExc_ValueError, \
 						"empty keys are not allowed")
+#define RAISE_LOCKED(type) PyErr_SET_VIM(_(type " is locked"))
+#define RAISE_LOCKED_DICTIONARY RAISE_LOCKED("dictionary")
+#define RAISE_LOCKED_LIST RAISE_LOCKED("list")
+#define RAISE_UNDO_FAIL PyErr_SET_VIM("cannot save undo information")
+#define RAISE_LINE_FAIL(act) PyErr_SET_VIM("cannot " act " line")
+#define RAISE_KEY_ADD_FAIL(key) \
+    PyErr_VIM_FORMAT("failed to add key '%s' to dictionary", key)
+#define RAISE_INVALID_INDEX_TYPE(idx) \
+    PyErr_FORMAT(PyExc_TypeError, "index must be int or slice, not %s", \
+	    Py_TYPE_NAME(idx));
 
 #define INVALID_BUFFER_VALUE ((buf_T *)(-1))
 #define INVALID_WINDOW_VALUE ((win_T *)(-1))
@@ -122,7 +138,13 @@
     }
     else
     {
-	PyErr_SET_STRING(PyExc_TypeError, "object must be string");
+	PyErr_FORMAT(PyExc_TypeError,
+#if PY_MAJOR_VERSION < 3
+		"expected str() or unicode() instance, but got %s"
+#else
+		"expected bytes() or str() instance, but got %s"
+#endif
+		, Py_TYPE_NAME(object));
 	return NULL;
     }
 
@@ -231,7 +253,7 @@
 	return 0;
     }
 
-    PyErr_SET_STRING(PyExc_AttributeError, "invalid attribute");
+    PyErr_FORMAT(PyExc_AttributeError, "invalid attribute: %s", name);
     return -1;
 }
 
@@ -967,11 +989,19 @@
 {
     PyObject	*fd, *pathname, *description;
 
-    if (!PyTuple_Check(find_module_result)
-	    || PyTuple_GET_SIZE(find_module_result) != 3)
+    if (!PyTuple_Check(find_module_result))
     {
-	PyErr_SET_STRING(PyExc_TypeError,
-		"expected 3-tuple as imp.find_module() result");
+	PyErr_FORMAT(PyExc_TypeError,
+		"expected 3-tuple as imp.find_module() result, but got %s",
+		Py_TYPE_NAME(find_module_result));
+	return NULL;
+    }
+    if (PyTuple_GET_SIZE(find_module_result) != 3)
+    {
+	PyErr_FORMAT(PyExc_TypeError,
+		"expected 3-tuple as imp.find_module() result, but got "
+		"tuple of size %d",
+		(int) PyTuple_GET_SIZE(find_module_result));
 	return NULL;
     }
 
@@ -1377,7 +1407,7 @@
     }
     else
     {
-	PyErr_SET_STRING(PyExc_AttributeError, "cannot set this attribute");
+	PyErr_FORMAT(PyExc_AttributeError, "cannot set attribute %s", name);
 	return -1;
     }
 }
@@ -1459,7 +1489,7 @@
     {
 	if (dict->dv_lock)
 	{
-	    PyErr_SET_VIM("dict is locked");
+	    RAISE_LOCKED_DICTIONARY;
 	    Py_DECREF(r);
 	    return NULL;
 	}
@@ -1562,7 +1592,7 @@
 
     if (dict->dv_lock)
     {
-	PyErr_SET_VIM("dict is locked");
+	RAISE_LOCKED_DICTIONARY;
 	return -1;
     }
 
@@ -1614,10 +1644,10 @@
 
 	if (dict_add(dict, di) == FAIL)
 	{
-	    Py_XDECREF(todecref);
 	    vim_free(di);
 	    dictitem_free(di);
-	    PyErr_SET_VIM("failed to add key to dictionary");
+	    RAISE_KEY_ADD_FAIL(key);
+	    Py_XDECREF(todecref);
 	    return -1;
 	}
     }
@@ -1725,7 +1755,7 @@
 
     if (dict->dv_lock)
     {
-	PyErr_SET_VIM("dict is locked");
+	RAISE_LOCKED_DICTIONARY;
 	return NULL;
     }
 
@@ -1781,8 +1811,10 @@
 		{
 		    Py_DECREF(iterator);
 		    Py_DECREF(fast);
-		    PyErr_SET_STRING(PyExc_ValueError,
-			    "expected sequence element of size 2");
+		    PyErr_FORMAT(PyExc_ValueError,
+			    "expected sequence element of size 2, "
+			    "but got sequence of size %d",
+			    PySequence_Fast_GET_SIZE(fast));
 		    return NULL;
 		}
 
@@ -1823,9 +1855,9 @@
 
 		if (dict_add(dict, di) == FAIL)
 		{
+		    RAISE_KEY_ADD_FAIL(di->di_key);
 		    Py_DECREF(iterator);
 		    dictitem_free(di);
-		    PyErr_SET_VIM("failed to add key to dictionary");
 		    return NULL;
 		}
 	    }
@@ -2085,7 +2117,9 @@
     li = list_find(self->list, (long) index);
     if (li == NULL)
     {
-	PyErr_SET_VIM("internal error: failed to get vim list item");
+	/* No more suitable format specifications in python-2.3 */
+	PyErr_VIM_FORMAT("internal error: failed to get vim list item %d",
+		(int) index);
 	return NULL;
     }
     return ConvertToPyObject(&li->li_tv);
@@ -2198,7 +2232,7 @@
 
     if (l->lv_lock)
     {
-	PyErr_SET_VIM("list is locked");
+	RAISE_LOCKED_LIST;
 	return -1;
     }
     if (index>length || (index==length && obj==NULL))
@@ -2252,7 +2286,7 @@
 
     if (l->lv_lock)
     {
-	PyErr_SET_VIM("list is locked");
+	RAISE_LOCKED_LIST;
 	return -1;
     }
 
@@ -2265,7 +2299,7 @@
 	li = list_find(l, (long) first);
 	if (li == NULL)
 	{
-	    PyErr_SET_VIM("internal error: no vim list item");
+	    PyErr_VIM_FORMAT("internal error: no vim list item %d", (int)first);
 	    return -1;
 	}
 	if (last > first)
@@ -2315,7 +2349,7 @@
 
     if (l->lv_lock)
     {
-	PyErr_SET_VIM("list is locked");
+	RAISE_LOCKED_LIST;
 	return NULL;
     }
 
@@ -2375,7 +2409,7 @@
     }
     else
     {
-	PyErr_SET_STRING(PyExc_AttributeError, "cannot set this attribute");
+	PyErr_FORMAT(PyExc_AttributeError, "cannot set attribute %s", name);
 	return -1;
     }
 }
@@ -2410,8 +2444,8 @@
     {
 	if (!translated_function_exists(name))
 	{
-	    PyErr_SET_STRING(PyExc_ValueError,
-		    "unnamed function does not exist");
+	    PyErr_FORMAT(PyExc_ValueError,
+		    "unnamed function %s does not exist", name);
 	    return NULL;
 	}
 	self->name = vim_strsave(name);
@@ -2422,7 +2456,7 @@
 				    vim_strchr(name, AUTOLOAD_CHAR) == NULL))
 		== NULL)
 	{
-	    PyErr_SET_STRING(PyExc_ValueError, "function does not exist");
+	    PyErr_FORMAT(PyExc_ValueError, "function %s does not exist", name);
 	    return NULL;
 	}
 
@@ -2515,7 +2549,7 @@
     else if (error != OK)
     {
 	result = NULL;
-	PyErr_SET_VIM("failed to run function");
+	PyErr_VIM_FORMAT("failed to run function %s", (char *)name);
     }
     else
 	result = ConvertToPyObject(&rettv);
@@ -2770,14 +2804,16 @@
     {
 	if (self->opt_type == SREQ_GLOBAL)
 	{
-	    PyErr_SET_STRING(PyExc_ValueError, "unable to unset global option");
+	    PyErr_FORMAT(PyExc_ValueError,
+		    "unable to unset global option %s", key);
 	    Py_XDECREF(todecref);
 	    return -1;
 	}
 	else if (!(flags & SOPT_GLOBAL))
 	{
-	    PyErr_SET_STRING(PyExc_ValueError, "unable to unset option "
-					       "without global value");
+	    PyErr_FORMAT(PyExc_ValueError,
+		    "unable to unset option %s "
+		    "which does not have global value", key);
 	    Py_XDECREF(todecref);
 	    return -1;
 	}
@@ -3195,7 +3231,7 @@
 
     if (strcmp(name, "buffer") == 0)
     {
-	PyErr_SET_STRING(PyExc_TypeError, "readonly attribute");
+	PyErr_SET_STRING(PyExc_TypeError, "readonly attribute: buffer");
 	return -1;
     }
     else if (strcmp(name, "cursor") == 0)
@@ -3558,9 +3594,9 @@
 	VimTryStart();
 
 	if (u_savedel((linenr_T)n, 1L) == FAIL)
-	    PyErr_SET_VIM("cannot save undo information");
+	    RAISE_UNDO_FAIL;
 	else if (ml_delete((linenr_T)n, FALSE) == FAIL)
-	    PyErr_SET_VIM("cannot delete line");
+	    RAISE_LINE_FAIL("delete");
 	else
 	{
 	    if (buf == savebuf)
@@ -3594,12 +3630,12 @@
 
 	if (u_savesub((linenr_T)n) == FAIL)
 	{
-	    PyErr_SET_VIM("cannot save undo information");
+	    RAISE_UNDO_FAIL;
 	    vim_free(save);
 	}
 	else if (ml_replace((linenr_T)n, (char_u *)save, FALSE) == FAIL)
 	{
-	    PyErr_SET_VIM("cannot replace line");
+	    RAISE_LINE_FAIL("replace");
 	    vim_free(save);
 	}
 	else
@@ -3654,14 +3690,14 @@
 	switch_buffer(&savebuf, buf);
 
 	if (u_savedel((linenr_T)lo, (long)n) == FAIL)
-	    PyErr_SET_VIM("cannot save undo information");
+	    RAISE_UNDO_FAIL;
 	else
 	{
 	    for (i = 0; i < n; ++i)
 	    {
 		if (ml_delete((linenr_T)lo, FALSE) == FAIL)
 		{
-		    PyErr_SET_VIM("cannot delete line");
+		    RAISE_LINE_FAIL("delete");
 		    break;
 		}
 	    }
@@ -3722,7 +3758,7 @@
 	switch_buffer(&savebuf, buf);
 
 	if (u_save((linenr_T)(lo-1), (linenr_T)hi) == FAIL)
-	    PyErr_SET_VIM("cannot save undo information");
+	    RAISE_UNDO_FAIL;
 
 	/* If the size of the range is reducing (ie, new_len < old_len) we
 	 * need to delete some old_len. We do this at the start, by
@@ -3733,7 +3769,7 @@
 	    for (i = 0; i < old_len - new_len; ++i)
 		if (ml_delete((linenr_T)lo, FALSE) == FAIL)
 		{
-		    PyErr_SET_VIM("cannot delete line");
+		    RAISE_LINE_FAIL("delete");
 		    break;
 		}
 	    extra -= i;
@@ -3749,7 +3785,7 @@
 		if (ml_replace((linenr_T)(lo+i), (char_u *)array[i], FALSE)
 								      == FAIL)
 		{
-		    PyErr_SET_VIM("cannot replace line");
+		    RAISE_LINE_FAIL("replace");
 		    break;
 		}
 	}
@@ -3767,7 +3803,7 @@
 		if (ml_append((linenr_T)(lo + i - 1),
 					(char_u *)array[i], 0, FALSE) == FAIL)
 		{
-		    PyErr_SET_VIM("cannot insert line");
+		    RAISE_LINE_FAIL("insert");
 		    break;
 		}
 		vim_free(array[i]);
@@ -3844,9 +3880,9 @@
 	switch_buffer(&savebuf, buf);
 
 	if (u_save((linenr_T)n, (linenr_T)(n+1)) == FAIL)
-	    PyErr_SET_VIM("cannot save undo information");
+	    RAISE_UNDO_FAIL;
 	else if (ml_append((linenr_T)n, (char_u *)str, 0, FALSE) == FAIL)
-	    PyErr_SET_VIM("cannot insert line");
+	    RAISE_LINE_FAIL("insert");
 	else
 	    appended_lines_mark((linenr_T)n, 1L);
 
@@ -3895,7 +3931,7 @@
 	switch_buffer(&savebuf, buf);
 
 	if (u_save((linenr_T)n, (linenr_T)(n + 1)) == FAIL)
-	    PyErr_SET_VIM("cannot save undo information");
+	    RAISE_UNDO_FAIL;
 	else
 	{
 	    for (i = 0; i < size; ++i)
@@ -3903,7 +3939,7 @@
 		if (ml_append((linenr_T)(n + i),
 					(char_u *)array[i], 0, FALSE) == FAIL)
 		{
-		    PyErr_SET_VIM("cannot insert line");
+		    RAISE_LINE_FAIL("insert");
 
 		    /* Free the rest of the lines */
 		    while (i < size)
@@ -4668,7 +4704,9 @@
 
 	if (value->ob_type != &BufferType)
 	{
-	    PyErr_SET_STRING(PyExc_TypeError, "expected vim.Buffer object");
+	    PyErr_FORMAT(PyExc_TypeError,
+		    "expected vim.Buffer object, but got %s",
+		    Py_TYPE_NAME(value));
 	    return -1;
 	}
 
@@ -4681,7 +4719,7 @@
 	{
 	    if (VimTryEnd())
 		return -1;
-	    PyErr_SET_VIM("failed to switch to given buffer");
+	    PyErr_VIM_FORMAT("failed to switch to buffer %d", count);
 	    return -1;
 	}
 
@@ -4693,7 +4731,9 @@
 
 	if (value->ob_type != &WindowType)
 	{
-	    PyErr_SET_STRING(PyExc_TypeError, "expected vim.Window object");
+	    PyErr_FORMAT(PyExc_TypeError,
+		    "expected vim.Window object, but got %s",
+		    Py_TYPE_NAME(value));
 	    return -1;
 	}
 
@@ -4725,7 +4765,9 @@
     {
 	if (value->ob_type != &TabPageType)
 	{
-	    PyErr_SET_STRING(PyExc_TypeError, "expected vim.TabPage object");
+	    PyErr_FORMAT(PyExc_TypeError,
+		    "expected vim.TabPage object, but got %s",
+		    Py_TYPE_NAME(value));
 	    return -1;
 	}
 
@@ -5003,10 +5045,10 @@
 
 	if (dict_add(dict, di) == FAIL)
 	{
+	    RAISE_KEY_ADD_FAIL(di->di_key);
 	    clear_tv(&di->di_tv);
 	    vim_free(di);
 	    dict_unref(dict);
-	    PyErr_SET_VIM("failed to add key to dictionary");
 	    return -1;
 	}
     }
@@ -5105,10 +5147,10 @@
 
 	if (dict_add(dict, di) == FAIL)
 	{
+	    RAISE_KEY_ADD_FAIL(di->di_key);
 	    Py_DECREF(iterator);
 	    dictitem_free(di);
 	    dict_unref(dict);
-	    PyErr_SET_VIM("failed to add key to dictionary");
 	    return -1;
 	}
     }
@@ -5216,8 +5258,9 @@
 	r = convert_dl(obj, tv, pymap_to_tv, lookup_dict);
     else
     {
-	PyErr_SET_STRING(PyExc_TypeError,
-		"unable to convert object to vim dictionary");
+	PyErr_FORMAT(PyExc_TypeError,
+		"unable to convert %s to vim dictionary",
+		Py_TYPE_NAME(obj));
 	r = -1;
     }
     Py_DECREF(lookup_dict);
@@ -5326,8 +5369,9 @@
 	return convert_dl(obj, tv, pymap_to_tv, lookup_dict);
     else
     {
-	PyErr_SET_STRING(PyExc_TypeError,
-		"unable to convert to vim structure");
+	PyErr_FORMAT(PyExc_TypeError,
+		"unable to convert %s to vim structure",
+		Py_TYPE_NAME(obj));
 	return -1;
     }
     return 0;
@@ -5338,7 +5382,7 @@
 {
     if (tv == NULL)
     {
-	PyErr_SET_VIM("NULL reference passed");
+	PyErr_SET_VIM("internal error: NULL reference passed");
 	return NULL;
     }
     switch (tv->v_type)
diff --git a/src/if_python.c b/src/if_python.c
index ed51119..28cd36f 100644
--- a/src/if_python.c
+++ b/src/if_python.c
@@ -160,6 +160,7 @@
 # define PyErr_BadArgument dll_PyErr_BadArgument
 # define PyErr_NewException dll_PyErr_NewException
 # define PyErr_Clear dll_PyErr_Clear
+# define PyErr_Format dll_PyErr_Format
 # define PyErr_PrintEx dll_PyErr_PrintEx
 # define PyErr_NoMemory dll_PyErr_NoMemory
 # define PyErr_Occurred dll_PyErr_Occurred
@@ -301,6 +302,7 @@
 static int(*dll_PyErr_BadArgument)(void);
 static PyObject *(*dll_PyErr_NewException)(char *, PyObject *, PyObject *);
 static void(*dll_PyErr_Clear)(void);
+static PyObject*(*dll_PyErr_Format)(PyObject *, const char *, ...);
 static void(*dll_PyErr_PrintEx)(int);
 static PyObject*(*dll_PyErr_NoMemory)(void);
 static PyObject*(*dll_PyErr_Occurred)(void);
@@ -473,6 +475,7 @@
     {"PyErr_BadArgument", (PYTHON_PROC*)&dll_PyErr_BadArgument},
     {"PyErr_NewException", (PYTHON_PROC*)&dll_PyErr_NewException},
     {"PyErr_Clear", (PYTHON_PROC*)&dll_PyErr_Clear},
+    {"PyErr_Format", (PYTHON_PROC*)&dll_PyErr_Format},
     {"PyErr_PrintEx", (PYTHON_PROC*)&dll_PyErr_PrintEx},
     {"PyErr_NoMemory", (PYTHON_PROC*)&dll_PyErr_NoMemory},
     {"PyErr_Occurred", (PYTHON_PROC*)&dll_PyErr_Occurred},
diff --git a/src/if_python3.c b/src/if_python3.c
index 7155bc1..9bb2a4f 100644
--- a/src/if_python3.c
+++ b/src/if_python3.c
@@ -122,6 +122,7 @@
 # define PyDict_SetItemString py3_PyDict_SetItemString
 # define PyErr_BadArgument py3_PyErr_BadArgument
 # define PyErr_Clear py3_PyErr_Clear
+# define PyErr_Format py3_PyErr_Format
 # define PyErr_PrintEx py3_PyErr_PrintEx
 # define PyErr_NoMemory py3_PyErr_NoMemory
 # define PyErr_Occurred py3_PyErr_Occurred
@@ -337,6 +338,7 @@
 static void* (*py3_PyMem_Malloc)(size_t);
 static int (*py3_Py_IsInitialized)(void);
 static void (*py3_PyErr_Clear)(void);
+static PyObject* (*py3_PyErr_Format)(PyObject *, const char *, ...);
 static void (*py3_PyErr_PrintEx)(int);
 static PyObject*(*py3__PyObject_Init)(PyObject *, PyTypeObject *);
 static iternextfunc py3__PyObject_NextNotImplemented;
@@ -485,6 +487,7 @@
     {"_Py_FalseStruct", (PYTHON_PROC*)&py3__Py_FalseStruct},
     {"_Py_TrueStruct", (PYTHON_PROC*)&py3__Py_TrueStruct},
     {"PyErr_Clear", (PYTHON_PROC*)&py3_PyErr_Clear},
+    {"PyErr_Format", (PYTHON_PROC*)&py3_PyErr_Format},
     {"PyErr_PrintEx", (PYTHON_PROC*)&py3_PyErr_PrintEx},
     {"PyObject_Init", (PYTHON_PROC*)&py3__PyObject_Init},
     {"PyModule_AddObject", (PYTHON_PROC*)&py3_PyModule_AddObject},
@@ -1169,7 +1172,7 @@
     }
     else
     {
-	PyErr_SET_STRING(PyExc_TypeError, "index must be int or slice");
+	RAISE_INVALID_INDEX_TYPE(idx);
 	return NULL;
     }
 }
@@ -1203,7 +1206,7 @@
     }
     else
     {
-	PyErr_SET_STRING(PyExc_TypeError, "index must be int or slice");
+	RAISE_INVALID_INDEX_TYPE(idx);
 	return -1;
     }
 }
@@ -1285,7 +1288,7 @@
     }
     else
     {
-	PyErr_SET_STRING(PyExc_TypeError, "index must be int or slice");
+	RAISE_INVALID_INDEX_TYPE(idx);
 	return NULL;
     }
 }
@@ -1312,7 +1315,7 @@
     }
     else
     {
-	PyErr_SET_STRING(PyExc_TypeError, "index must be int or slice");
+	RAISE_INVALID_INDEX_TYPE(idx);
 	return -1;
     }
 }
@@ -1491,7 +1494,7 @@
     }
     else
     {
-	PyErr_SET_STRING(PyExc_TypeError, "index must be int or slice");
+	RAISE_INVALID_INDEX_TYPE(idx);
 	return NULL;
     }
 }
@@ -1515,7 +1518,7 @@
     }
     else
     {
-	PyErr_SET_STRING(PyExc_TypeError, "index must be int or slice");
+	RAISE_INVALID_INDEX_TYPE(idx);
 	return -1;
     }
 }
diff --git a/src/testdir/test86.ok b/src/testdir/test86.ok
index 27a1372..d94e0ea 100644
--- a/src/testdir/test86.ok
+++ b/src/testdir/test86.ok
@@ -439,106 +439,106 @@
 >> OutputSetattr
 del sys.stdout.softspace:AttributeError:("can't delete OutputObject attributes",)
 sys.stdout.softspace = []:TypeError:('softspace must be an integer',)
-sys.stdout.attr = None:AttributeError:('invalid attribute',)
+sys.stdout.attr = None:AttributeError:('invalid attribute: attr',)
 >> OutputWrite
 sys.stdout.write(None):TypeError:('coercing to Unicode: need string or buffer, NoneType found',)
 >> OutputWriteLines
 sys.stdout.writelines(None):TypeError:("'NoneType' object is not iterable",)
 sys.stdout.writelines([1]):TypeError:('coercing to Unicode: need string or buffer, int found',)
 > VimCommand
-vim.command(1):TypeError:('object must be string',)
+vim.command(1):TypeError:('expected str() or unicode() instance, but got int',)
 > VimToPython
 > VimEval
-vim.eval(1):TypeError:('object must be string',)
+vim.eval(1):TypeError:('expected str() or unicode() instance, but got int',)
 > VimEvalPy
-vim.bindeval(1):TypeError:('object must be string',)
+vim.bindeval(1):TypeError:('expected str() or unicode() instance, but got int',)
 > VimStrwidth
-vim.strwidth(1):TypeError:('object must be string',)
+vim.strwidth(1):TypeError:('expected str() or unicode() instance, but got int',)
 > Dictionary
 >> DictionaryConstructor
-vim.Dictionary("abc"):ValueError:('expected sequence element of size 2',)
+vim.Dictionary("abc"):ValueError:('expected sequence element of size 2, but got sequence of size 1',)
 >> DictionarySetattr
 del d.locked:AttributeError:('cannot delete vim.Dictionary attributes',)
 d.locked = FailingTrue():NotImplementedError:()
 vim.vvars.locked = False:TypeError:('cannot modify fixed dictionary',)
-d.scope = True:AttributeError:('cannot set this attribute',)
-d.xxx = True:AttributeError:('cannot set this attribute',)
+d.scope = True:AttributeError:('cannot set attribute scope',)
+d.xxx = True:AttributeError:('cannot set attribute xxx',)
 >> _DictionaryItem
 d.get("a", 2, 3):TypeError:('function takes at most 2 arguments (3 given)',)
 >>> Testing StringToChars using d.get(%s)
-d.get(1):TypeError:('object must be string',)
+d.get(1):TypeError:('expected str() or unicode() instance, but got int',)
 d.get(u"\0"):TypeError:('expected string without null bytes',)
 d.get("\0"):TypeError:('expected string without null bytes',)
 <<< Finished
 d.pop("a"):KeyError:('a',)
-dl.pop("a"):error:('dict is locked',)
+dl.pop("a"):error:('dictionary is locked',)
 >> DictionaryIterNext
 for i in ned: ned["a"] = 1:RuntimeError:('hashtab changed during iteration',)
 >> DictionaryAssItem
-dl["b"] = 1:error:('dict is locked',)
+dl["b"] = 1:error:('dictionary is locked',)
 >>> Testing StringToChars using d[%s] = 1
-d[1] = 1:TypeError:('object must be string',)
+d[1] = 1:TypeError:('expected str() or unicode() instance, but got int',)
 d[u"\0"] = 1:TypeError:('expected string without null bytes',)
 d["\0"] = 1:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d["a"] = {%s : 1}
-d["a"] = {1 : 1}:TypeError:('object must be string',)
+d["a"] = {1 : 1}:TypeError:('expected str() or unicode() instance, but got int',)
 d["a"] = {u"\0" : 1}:TypeError:('expected string without null bytes',)
 d["a"] = {"\0" : 1}:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d["a"] = {"abc" : {%s : 1}}
-d["a"] = {"abc" : {1 : 1}}:TypeError:('object must be string',)
+d["a"] = {"abc" : {1 : 1}}:TypeError:('expected str() or unicode() instance, but got int',)
 d["a"] = {"abc" : {u"\0" : 1}}:TypeError:('expected string without null bytes',)
 d["a"] = {"abc" : {"\0" : 1}}:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d["a"] = {"abc" : Mapping({%s : 1})}
-d["a"] = {"abc" : Mapping({1 : 1})}:TypeError:('object must be string',)
+d["a"] = {"abc" : Mapping({1 : 1})}:TypeError:('expected str() or unicode() instance, but got int',)
 d["a"] = {"abc" : Mapping({u"\0" : 1})}:TypeError:('expected string without null bytes',)
 d["a"] = {"abc" : Mapping({"\0" : 1})}:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using d["a"] = {"abc" : %s}
-d["a"] = {"abc" : FailingIter()}:TypeError:('unable to convert to vim structure',)
+d["a"] = {"abc" : FailingIter()}:TypeError:('unable to convert FailingIter to vim structure',)
 d["a"] = {"abc" : FailingIterNext()}:NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using d["a"] = {"abc" : %s}
-d["a"] = {"abc" : None}:TypeError:('unable to convert to vim structure',)
+d["a"] = {"abc" : None}:TypeError:('unable to convert NoneType to vim structure',)
 d["a"] = {"abc" : {"": 1}}:ValueError:('empty keys are not allowed',)
 d["a"] = {"abc" : {u"": 1}}:ValueError:('empty keys are not allowed',)
 d["a"] = {"abc" : FailingMapping()}:NotImplementedError:()
 d["a"] = {"abc" : FailingMappingKey()}:NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using d["a"] = Mapping({%s : 1})
-d["a"] = Mapping({1 : 1}):TypeError:('object must be string',)
+d["a"] = Mapping({1 : 1}):TypeError:('expected str() or unicode() instance, but got int',)
 d["a"] = Mapping({u"\0" : 1}):TypeError:('expected string without null bytes',)
 d["a"] = Mapping({"\0" : 1}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d["a"] = Mapping({"abc" : {%s : 1}})
-d["a"] = Mapping({"abc" : {1 : 1}}):TypeError:('object must be string',)
+d["a"] = Mapping({"abc" : {1 : 1}}):TypeError:('expected str() or unicode() instance, but got int',)
 d["a"] = Mapping({"abc" : {u"\0" : 1}}):TypeError:('expected string without null bytes',)
 d["a"] = Mapping({"abc" : {"\0" : 1}}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d["a"] = Mapping({"abc" : Mapping({%s : 1})})
-d["a"] = Mapping({"abc" : Mapping({1 : 1})}):TypeError:('object must be string',)
+d["a"] = Mapping({"abc" : Mapping({1 : 1})}):TypeError:('expected str() or unicode() instance, but got int',)
 d["a"] = Mapping({"abc" : Mapping({u"\0" : 1})}):TypeError:('expected string without null bytes',)
 d["a"] = Mapping({"abc" : Mapping({"\0" : 1})}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using d["a"] = Mapping({"abc" : %s})
-d["a"] = Mapping({"abc" : FailingIter()}):TypeError:('unable to convert to vim structure',)
+d["a"] = Mapping({"abc" : FailingIter()}):TypeError:('unable to convert FailingIter to vim structure',)
 d["a"] = Mapping({"abc" : FailingIterNext()}):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using d["a"] = Mapping({"abc" : %s})
-d["a"] = Mapping({"abc" : None}):TypeError:('unable to convert to vim structure',)
+d["a"] = Mapping({"abc" : None}):TypeError:('unable to convert NoneType to vim structure',)
 d["a"] = Mapping({"abc" : {"": 1}}):ValueError:('empty keys are not allowed',)
 d["a"] = Mapping({"abc" : {u"": 1}}):ValueError:('empty keys are not allowed',)
 d["a"] = Mapping({"abc" : FailingMapping()}):NotImplementedError:()
 d["a"] = Mapping({"abc" : FailingMappingKey()}):NotImplementedError:()
 <<< Finished
 >>> Testing *Iter* using d["a"] = %s
-d["a"] = FailingIter():TypeError:('unable to convert to vim structure',)
+d["a"] = FailingIter():TypeError:('unable to convert FailingIter to vim structure',)
 d["a"] = FailingIterNext():NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using d["a"] = %s
-d["a"] = None:TypeError:('unable to convert to vim structure',)
+d["a"] = None:TypeError:('unable to convert NoneType to vim structure',)
 d["a"] = {"": 1}:ValueError:('empty keys are not allowed',)
 d["a"] = {u"": 1}:ValueError:('empty keys are not allowed',)
 d["a"] = FailingMapping():NotImplementedError:()
@@ -550,52 +550,52 @@
 d.update(FailingMapping()):NotImplementedError:()
 d.update([FailingIterNext()]):NotImplementedError:()
 >>> Testing StringToChars using d.update({%s : 1})
-d.update({1 : 1}):TypeError:('object must be string',)
+d.update({1 : 1}):TypeError:('expected str() or unicode() instance, but got int',)
 d.update({u"\0" : 1}):TypeError:('expected string without null bytes',)
 d.update({"\0" : 1}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d.update({"abc" : {%s : 1}})
-d.update({"abc" : {1 : 1}}):TypeError:('object must be string',)
+d.update({"abc" : {1 : 1}}):TypeError:('expected str() or unicode() instance, but got int',)
 d.update({"abc" : {u"\0" : 1}}):TypeError:('expected string without null bytes',)
 d.update({"abc" : {"\0" : 1}}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d.update({"abc" : Mapping({%s : 1})})
-d.update({"abc" : Mapping({1 : 1})}):TypeError:('object must be string',)
+d.update({"abc" : Mapping({1 : 1})}):TypeError:('expected str() or unicode() instance, but got int',)
 d.update({"abc" : Mapping({u"\0" : 1})}):TypeError:('expected string without null bytes',)
 d.update({"abc" : Mapping({"\0" : 1})}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using d.update({"abc" : %s})
-d.update({"abc" : FailingIter()}):TypeError:('unable to convert to vim structure',)
+d.update({"abc" : FailingIter()}):TypeError:('unable to convert FailingIter to vim structure',)
 d.update({"abc" : FailingIterNext()}):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update({"abc" : %s})
-d.update({"abc" : None}):TypeError:('unable to convert to vim structure',)
+d.update({"abc" : None}):TypeError:('unable to convert NoneType to vim structure',)
 d.update({"abc" : {"": 1}}):ValueError:('empty keys are not allowed',)
 d.update({"abc" : {u"": 1}}):ValueError:('empty keys are not allowed',)
 d.update({"abc" : FailingMapping()}):NotImplementedError:()
 d.update({"abc" : FailingMappingKey()}):NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using d.update(Mapping({%s : 1}))
-d.update(Mapping({1 : 1})):TypeError:('object must be string',)
+d.update(Mapping({1 : 1})):TypeError:('expected str() or unicode() instance, but got int',)
 d.update(Mapping({u"\0" : 1})):TypeError:('expected string without null bytes',)
 d.update(Mapping({"\0" : 1})):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d.update(Mapping({"abc" : {%s : 1}}))
-d.update(Mapping({"abc" : {1 : 1}})):TypeError:('object must be string',)
+d.update(Mapping({"abc" : {1 : 1}})):TypeError:('expected str() or unicode() instance, but got int',)
 d.update(Mapping({"abc" : {u"\0" : 1}})):TypeError:('expected string without null bytes',)
 d.update(Mapping({"abc" : {"\0" : 1}})):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d.update(Mapping({"abc" : Mapping({%s : 1})}))
-d.update(Mapping({"abc" : Mapping({1 : 1})})):TypeError:('object must be string',)
+d.update(Mapping({"abc" : Mapping({1 : 1})})):TypeError:('expected str() or unicode() instance, but got int',)
 d.update(Mapping({"abc" : Mapping({u"\0" : 1})})):TypeError:('expected string without null bytes',)
 d.update(Mapping({"abc" : Mapping({"\0" : 1})})):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using d.update(Mapping({"abc" : %s}))
-d.update(Mapping({"abc" : FailingIter()})):TypeError:('unable to convert to vim structure',)
+d.update(Mapping({"abc" : FailingIter()})):TypeError:('unable to convert FailingIter to vim structure',)
 d.update(Mapping({"abc" : FailingIterNext()})):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update(Mapping({"abc" : %s}))
-d.update(Mapping({"abc" : None})):TypeError:('unable to convert to vim structure',)
+d.update(Mapping({"abc" : None})):TypeError:('unable to convert NoneType to vim structure',)
 d.update(Mapping({"abc" : {"": 1}})):ValueError:('empty keys are not allowed',)
 d.update(Mapping({"abc" : {u"": 1}})):ValueError:('empty keys are not allowed',)
 d.update(Mapping({"abc" : FailingMapping()})):NotImplementedError:()
@@ -613,68 +613,68 @@
 d.update(FailingMappingKey()):NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using d.update(((%s, 0),))
-d.update(((1, 0),)):TypeError:('object must be string',)
+d.update(((1, 0),)):TypeError:('expected str() or unicode() instance, but got int',)
 d.update(((u"\0", 0),)):TypeError:('expected string without null bytes',)
 d.update((("\0", 0),)):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d.update((("a", {%s : 1}),))
-d.update((("a", {1 : 1}),)):TypeError:('object must be string',)
+d.update((("a", {1 : 1}),)):TypeError:('expected str() or unicode() instance, but got int',)
 d.update((("a", {u"\0" : 1}),)):TypeError:('expected string without null bytes',)
 d.update((("a", {"\0" : 1}),)):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d.update((("a", {"abc" : {%s : 1}}),))
-d.update((("a", {"abc" : {1 : 1}}),)):TypeError:('object must be string',)
+d.update((("a", {"abc" : {1 : 1}}),)):TypeError:('expected str() or unicode() instance, but got int',)
 d.update((("a", {"abc" : {u"\0" : 1}}),)):TypeError:('expected string without null bytes',)
 d.update((("a", {"abc" : {"\0" : 1}}),)):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d.update((("a", {"abc" : Mapping({%s : 1})}),))
-d.update((("a", {"abc" : Mapping({1 : 1})}),)):TypeError:('object must be string',)
+d.update((("a", {"abc" : Mapping({1 : 1})}),)):TypeError:('expected str() or unicode() instance, but got int',)
 d.update((("a", {"abc" : Mapping({u"\0" : 1})}),)):TypeError:('expected string without null bytes',)
 d.update((("a", {"abc" : Mapping({"\0" : 1})}),)):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using d.update((("a", {"abc" : %s}),))
-d.update((("a", {"abc" : FailingIter()}),)):TypeError:('unable to convert to vim structure',)
+d.update((("a", {"abc" : FailingIter()}),)):TypeError:('unable to convert FailingIter to vim structure',)
 d.update((("a", {"abc" : FailingIterNext()}),)):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update((("a", {"abc" : %s}),))
-d.update((("a", {"abc" : None}),)):TypeError:('unable to convert to vim structure',)
+d.update((("a", {"abc" : None}),)):TypeError:('unable to convert NoneType to vim structure',)
 d.update((("a", {"abc" : {"": 1}}),)):ValueError:('empty keys are not allowed',)
 d.update((("a", {"abc" : {u"": 1}}),)):ValueError:('empty keys are not allowed',)
 d.update((("a", {"abc" : FailingMapping()}),)):NotImplementedError:()
 d.update((("a", {"abc" : FailingMappingKey()}),)):NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using d.update((("a", Mapping({%s : 1})),))
-d.update((("a", Mapping({1 : 1})),)):TypeError:('object must be string',)
+d.update((("a", Mapping({1 : 1})),)):TypeError:('expected str() or unicode() instance, but got int',)
 d.update((("a", Mapping({u"\0" : 1})),)):TypeError:('expected string without null bytes',)
 d.update((("a", Mapping({"\0" : 1})),)):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d.update((("a", Mapping({"abc" : {%s : 1}})),))
-d.update((("a", Mapping({"abc" : {1 : 1}})),)):TypeError:('object must be string',)
+d.update((("a", Mapping({"abc" : {1 : 1}})),)):TypeError:('expected str() or unicode() instance, but got int',)
 d.update((("a", Mapping({"abc" : {u"\0" : 1}})),)):TypeError:('expected string without null bytes',)
 d.update((("a", Mapping({"abc" : {"\0" : 1}})),)):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using d.update((("a", Mapping({"abc" : Mapping({%s : 1})})),))
-d.update((("a", Mapping({"abc" : Mapping({1 : 1})})),)):TypeError:('object must be string',)
+d.update((("a", Mapping({"abc" : Mapping({1 : 1})})),)):TypeError:('expected str() or unicode() instance, but got int',)
 d.update((("a", Mapping({"abc" : Mapping({u"\0" : 1})})),)):TypeError:('expected string without null bytes',)
 d.update((("a", Mapping({"abc" : Mapping({"\0" : 1})})),)):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using d.update((("a", Mapping({"abc" : %s})),))
-d.update((("a", Mapping({"abc" : FailingIter()})),)):TypeError:('unable to convert to vim structure',)
+d.update((("a", Mapping({"abc" : FailingIter()})),)):TypeError:('unable to convert FailingIter to vim structure',)
 d.update((("a", Mapping({"abc" : FailingIterNext()})),)):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update((("a", Mapping({"abc" : %s})),))
-d.update((("a", Mapping({"abc" : None})),)):TypeError:('unable to convert to vim structure',)
+d.update((("a", Mapping({"abc" : None})),)):TypeError:('unable to convert NoneType to vim structure',)
 d.update((("a", Mapping({"abc" : {"": 1}})),)):ValueError:('empty keys are not allowed',)
 d.update((("a", Mapping({"abc" : {u"": 1}})),)):ValueError:('empty keys are not allowed',)
 d.update((("a", Mapping({"abc" : FailingMapping()})),)):NotImplementedError:()
 d.update((("a", Mapping({"abc" : FailingMappingKey()})),)):NotImplementedError:()
 <<< Finished
 >>> Testing *Iter* using d.update((("a", %s),))
-d.update((("a", FailingIter()),)):TypeError:('unable to convert to vim structure',)
+d.update((("a", FailingIter()),)):TypeError:('unable to convert FailingIter to vim structure',)
 d.update((("a", FailingIterNext()),)):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update((("a", %s),))
-d.update((("a", None),)):TypeError:('unable to convert to vim structure',)
+d.update((("a", None),)):TypeError:('unable to convert NoneType to vim structure',)
 d.update((("a", {"": 1}),)):ValueError:('empty keys are not allowed',)
 d.update((("a", {u"": 1}),)):ValueError:('empty keys are not allowed',)
 d.update((("a", FailingMapping()),)):NotImplementedError:()
@@ -689,63 +689,63 @@
 vim.List(1, 2):TypeError:('function takes at most 1 argument (2 given)',)
 vim.List(a=1):TypeError:('list constructor does not accept keyword arguments',)
 >>> Testing StringToChars using vim.List([{%s : 1}])
-vim.List([{1 : 1}]):TypeError:('object must be string',)
+vim.List([{1 : 1}]):TypeError:('expected str() or unicode() instance, but got int',)
 vim.List([{u"\0" : 1}]):TypeError:('expected string without null bytes',)
 vim.List([{"\0" : 1}]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using vim.List([{"abc" : {%s : 1}}])
-vim.List([{"abc" : {1 : 1}}]):TypeError:('object must be string',)
+vim.List([{"abc" : {1 : 1}}]):TypeError:('expected str() or unicode() instance, but got int',)
 vim.List([{"abc" : {u"\0" : 1}}]):TypeError:('expected string without null bytes',)
 vim.List([{"abc" : {"\0" : 1}}]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using vim.List([{"abc" : Mapping({%s : 1})}])
-vim.List([{"abc" : Mapping({1 : 1})}]):TypeError:('object must be string',)
+vim.List([{"abc" : Mapping({1 : 1})}]):TypeError:('expected str() or unicode() instance, but got int',)
 vim.List([{"abc" : Mapping({u"\0" : 1})}]):TypeError:('expected string without null bytes',)
 vim.List([{"abc" : Mapping({"\0" : 1})}]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using vim.List([{"abc" : %s}])
-vim.List([{"abc" : FailingIter()}]):TypeError:('unable to convert to vim structure',)
+vim.List([{"abc" : FailingIter()}]):TypeError:('unable to convert FailingIter to vim structure',)
 vim.List([{"abc" : FailingIterNext()}]):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using vim.List([{"abc" : %s}])
-vim.List([{"abc" : None}]):TypeError:('unable to convert to vim structure',)
+vim.List([{"abc" : None}]):TypeError:('unable to convert NoneType to vim structure',)
 vim.List([{"abc" : {"": 1}}]):ValueError:('empty keys are not allowed',)
 vim.List([{"abc" : {u"": 1}}]):ValueError:('empty keys are not allowed',)
 vim.List([{"abc" : FailingMapping()}]):NotImplementedError:()
 vim.List([{"abc" : FailingMappingKey()}]):NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using vim.List([Mapping({%s : 1})])
-vim.List([Mapping({1 : 1})]):TypeError:('object must be string',)
+vim.List([Mapping({1 : 1})]):TypeError:('expected str() or unicode() instance, but got int',)
 vim.List([Mapping({u"\0" : 1})]):TypeError:('expected string without null bytes',)
 vim.List([Mapping({"\0" : 1})]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using vim.List([Mapping({"abc" : {%s : 1}})])
-vim.List([Mapping({"abc" : {1 : 1}})]):TypeError:('object must be string',)
+vim.List([Mapping({"abc" : {1 : 1}})]):TypeError:('expected str() or unicode() instance, but got int',)
 vim.List([Mapping({"abc" : {u"\0" : 1}})]):TypeError:('expected string without null bytes',)
 vim.List([Mapping({"abc" : {"\0" : 1}})]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using vim.List([Mapping({"abc" : Mapping({%s : 1})})])
-vim.List([Mapping({"abc" : Mapping({1 : 1})})]):TypeError:('object must be string',)
+vim.List([Mapping({"abc" : Mapping({1 : 1})})]):TypeError:('expected str() or unicode() instance, but got int',)
 vim.List([Mapping({"abc" : Mapping({u"\0" : 1})})]):TypeError:('expected string without null bytes',)
 vim.List([Mapping({"abc" : Mapping({"\0" : 1})})]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using vim.List([Mapping({"abc" : %s})])
-vim.List([Mapping({"abc" : FailingIter()})]):TypeError:('unable to convert to vim structure',)
+vim.List([Mapping({"abc" : FailingIter()})]):TypeError:('unable to convert FailingIter to vim structure',)
 vim.List([Mapping({"abc" : FailingIterNext()})]):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using vim.List([Mapping({"abc" : %s})])
-vim.List([Mapping({"abc" : None})]):TypeError:('unable to convert to vim structure',)
+vim.List([Mapping({"abc" : None})]):TypeError:('unable to convert NoneType to vim structure',)
 vim.List([Mapping({"abc" : {"": 1}})]):ValueError:('empty keys are not allowed',)
 vim.List([Mapping({"abc" : {u"": 1}})]):ValueError:('empty keys are not allowed',)
 vim.List([Mapping({"abc" : FailingMapping()})]):NotImplementedError:()
 vim.List([Mapping({"abc" : FailingMappingKey()})]):NotImplementedError:()
 <<< Finished
 >>> Testing *Iter* using vim.List([%s])
-vim.List([FailingIter()]):TypeError:('unable to convert to vim structure',)
+vim.List([FailingIter()]):TypeError:('unable to convert FailingIter to vim structure',)
 vim.List([FailingIterNext()]):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using vim.List([%s])
-vim.List([None]):TypeError:('unable to convert to vim structure',)
+vim.List([None]):TypeError:('unable to convert NoneType to vim structure',)
 vim.List([{"": 1}]):ValueError:('empty keys are not allowed',)
 vim.List([{u"": 1}]):ValueError:('empty keys are not allowed',)
 vim.List([FailingMapping()]):NotImplementedError:()
@@ -759,63 +759,63 @@
 >> ListAssSlice
 ll[1:100] = "abc":error:('list is locked',)
 >>> Testing StringToChars using l[:] = [{%s : 1}]
-l[:] = [{1 : 1}]:TypeError:('object must be string',)
+l[:] = [{1 : 1}]:TypeError:('expected str() or unicode() instance, but got int',)
 l[:] = [{u"\0" : 1}]:TypeError:('expected string without null bytes',)
 l[:] = [{"\0" : 1}]:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using l[:] = [{"abc" : {%s : 1}}]
-l[:] = [{"abc" : {1 : 1}}]:TypeError:('object must be string',)
+l[:] = [{"abc" : {1 : 1}}]:TypeError:('expected str() or unicode() instance, but got int',)
 l[:] = [{"abc" : {u"\0" : 1}}]:TypeError:('expected string without null bytes',)
 l[:] = [{"abc" : {"\0" : 1}}]:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using l[:] = [{"abc" : Mapping({%s : 1})}]
-l[:] = [{"abc" : Mapping({1 : 1})}]:TypeError:('object must be string',)
+l[:] = [{"abc" : Mapping({1 : 1})}]:TypeError:('expected str() or unicode() instance, but got int',)
 l[:] = [{"abc" : Mapping({u"\0" : 1})}]:TypeError:('expected string without null bytes',)
 l[:] = [{"abc" : Mapping({"\0" : 1})}]:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using l[:] = [{"abc" : %s}]
-l[:] = [{"abc" : FailingIter()}]:TypeError:('unable to convert to vim structure',)
+l[:] = [{"abc" : FailingIter()}]:TypeError:('unable to convert FailingIter to vim structure',)
 l[:] = [{"abc" : FailingIterNext()}]:NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using l[:] = [{"abc" : %s}]
-l[:] = [{"abc" : None}]:TypeError:('unable to convert to vim structure',)
+l[:] = [{"abc" : None}]:TypeError:('unable to convert NoneType to vim structure',)
 l[:] = [{"abc" : {"": 1}}]:ValueError:('empty keys are not allowed',)
 l[:] = [{"abc" : {u"": 1}}]:ValueError:('empty keys are not allowed',)
 l[:] = [{"abc" : FailingMapping()}]:NotImplementedError:()
 l[:] = [{"abc" : FailingMappingKey()}]:NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using l[:] = [Mapping({%s : 1})]
-l[:] = [Mapping({1 : 1})]:TypeError:('object must be string',)
+l[:] = [Mapping({1 : 1})]:TypeError:('expected str() or unicode() instance, but got int',)
 l[:] = [Mapping({u"\0" : 1})]:TypeError:('expected string without null bytes',)
 l[:] = [Mapping({"\0" : 1})]:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using l[:] = [Mapping({"abc" : {%s : 1}})]
-l[:] = [Mapping({"abc" : {1 : 1}})]:TypeError:('object must be string',)
+l[:] = [Mapping({"abc" : {1 : 1}})]:TypeError:('expected str() or unicode() instance, but got int',)
 l[:] = [Mapping({"abc" : {u"\0" : 1}})]:TypeError:('expected string without null bytes',)
 l[:] = [Mapping({"abc" : {"\0" : 1}})]:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using l[:] = [Mapping({"abc" : Mapping({%s : 1})})]
-l[:] = [Mapping({"abc" : Mapping({1 : 1})})]:TypeError:('object must be string',)
+l[:] = [Mapping({"abc" : Mapping({1 : 1})})]:TypeError:('expected str() or unicode() instance, but got int',)
 l[:] = [Mapping({"abc" : Mapping({u"\0" : 1})})]:TypeError:('expected string without null bytes',)
 l[:] = [Mapping({"abc" : Mapping({"\0" : 1})})]:TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using l[:] = [Mapping({"abc" : %s})]
-l[:] = [Mapping({"abc" : FailingIter()})]:TypeError:('unable to convert to vim structure',)
+l[:] = [Mapping({"abc" : FailingIter()})]:TypeError:('unable to convert FailingIter to vim structure',)
 l[:] = [Mapping({"abc" : FailingIterNext()})]:NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using l[:] = [Mapping({"abc" : %s})]
-l[:] = [Mapping({"abc" : None})]:TypeError:('unable to convert to vim structure',)
+l[:] = [Mapping({"abc" : None})]:TypeError:('unable to convert NoneType to vim structure',)
 l[:] = [Mapping({"abc" : {"": 1}})]:ValueError:('empty keys are not allowed',)
 l[:] = [Mapping({"abc" : {u"": 1}})]:ValueError:('empty keys are not allowed',)
 l[:] = [Mapping({"abc" : FailingMapping()})]:NotImplementedError:()
 l[:] = [Mapping({"abc" : FailingMappingKey()})]:NotImplementedError:()
 <<< Finished
 >>> Testing *Iter* using l[:] = [%s]
-l[:] = [FailingIter()]:TypeError:('unable to convert to vim structure',)
+l[:] = [FailingIter()]:TypeError:('unable to convert FailingIter to vim structure',)
 l[:] = [FailingIterNext()]:NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using l[:] = [%s]
-l[:] = [None]:TypeError:('unable to convert to vim structure',)
+l[:] = [None]:TypeError:('unable to convert NoneType to vim structure',)
 l[:] = [{"": 1}]:ValueError:('empty keys are not allowed',)
 l[:] = [{u"": 1}]:ValueError:('empty keys are not allowed',)
 l[:] = [FailingMapping()]:NotImplementedError:()
@@ -823,63 +823,63 @@
 <<< Finished
 >> ListConcatInPlace
 >>> Testing StringToChars using l.extend([{%s : 1}])
-l.extend([{1 : 1}]):TypeError:('object must be string',)
+l.extend([{1 : 1}]):TypeError:('expected str() or unicode() instance, but got int',)
 l.extend([{u"\0" : 1}]):TypeError:('expected string without null bytes',)
 l.extend([{"\0" : 1}]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using l.extend([{"abc" : {%s : 1}}])
-l.extend([{"abc" : {1 : 1}}]):TypeError:('object must be string',)
+l.extend([{"abc" : {1 : 1}}]):TypeError:('expected str() or unicode() instance, but got int',)
 l.extend([{"abc" : {u"\0" : 1}}]):TypeError:('expected string without null bytes',)
 l.extend([{"abc" : {"\0" : 1}}]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using l.extend([{"abc" : Mapping({%s : 1})}])
-l.extend([{"abc" : Mapping({1 : 1})}]):TypeError:('object must be string',)
+l.extend([{"abc" : Mapping({1 : 1})}]):TypeError:('expected str() or unicode() instance, but got int',)
 l.extend([{"abc" : Mapping({u"\0" : 1})}]):TypeError:('expected string without null bytes',)
 l.extend([{"abc" : Mapping({"\0" : 1})}]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using l.extend([{"abc" : %s}])
-l.extend([{"abc" : FailingIter()}]):TypeError:('unable to convert to vim structure',)
+l.extend([{"abc" : FailingIter()}]):TypeError:('unable to convert FailingIter to vim structure',)
 l.extend([{"abc" : FailingIterNext()}]):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using l.extend([{"abc" : %s}])
-l.extend([{"abc" : None}]):TypeError:('unable to convert to vim structure',)
+l.extend([{"abc" : None}]):TypeError:('unable to convert NoneType to vim structure',)
 l.extend([{"abc" : {"": 1}}]):ValueError:('empty keys are not allowed',)
 l.extend([{"abc" : {u"": 1}}]):ValueError:('empty keys are not allowed',)
 l.extend([{"abc" : FailingMapping()}]):NotImplementedError:()
 l.extend([{"abc" : FailingMappingKey()}]):NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using l.extend([Mapping({%s : 1})])
-l.extend([Mapping({1 : 1})]):TypeError:('object must be string',)
+l.extend([Mapping({1 : 1})]):TypeError:('expected str() or unicode() instance, but got int',)
 l.extend([Mapping({u"\0" : 1})]):TypeError:('expected string without null bytes',)
 l.extend([Mapping({"\0" : 1})]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using l.extend([Mapping({"abc" : {%s : 1}})])
-l.extend([Mapping({"abc" : {1 : 1}})]):TypeError:('object must be string',)
+l.extend([Mapping({"abc" : {1 : 1}})]):TypeError:('expected str() or unicode() instance, but got int',)
 l.extend([Mapping({"abc" : {u"\0" : 1}})]):TypeError:('expected string without null bytes',)
 l.extend([Mapping({"abc" : {"\0" : 1}})]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using l.extend([Mapping({"abc" : Mapping({%s : 1})})])
-l.extend([Mapping({"abc" : Mapping({1 : 1})})]):TypeError:('object must be string',)
+l.extend([Mapping({"abc" : Mapping({1 : 1})})]):TypeError:('expected str() or unicode() instance, but got int',)
 l.extend([Mapping({"abc" : Mapping({u"\0" : 1})})]):TypeError:('expected string without null bytes',)
 l.extend([Mapping({"abc" : Mapping({"\0" : 1})})]):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using l.extend([Mapping({"abc" : %s})])
-l.extend([Mapping({"abc" : FailingIter()})]):TypeError:('unable to convert to vim structure',)
+l.extend([Mapping({"abc" : FailingIter()})]):TypeError:('unable to convert FailingIter to vim structure',)
 l.extend([Mapping({"abc" : FailingIterNext()})]):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using l.extend([Mapping({"abc" : %s})])
-l.extend([Mapping({"abc" : None})]):TypeError:('unable to convert to vim structure',)
+l.extend([Mapping({"abc" : None})]):TypeError:('unable to convert NoneType to vim structure',)
 l.extend([Mapping({"abc" : {"": 1}})]):ValueError:('empty keys are not allowed',)
 l.extend([Mapping({"abc" : {u"": 1}})]):ValueError:('empty keys are not allowed',)
 l.extend([Mapping({"abc" : FailingMapping()})]):NotImplementedError:()
 l.extend([Mapping({"abc" : FailingMappingKey()})]):NotImplementedError:()
 <<< Finished
 >>> Testing *Iter* using l.extend([%s])
-l.extend([FailingIter()]):TypeError:('unable to convert to vim structure',)
+l.extend([FailingIter()]):TypeError:('unable to convert FailingIter to vim structure',)
 l.extend([FailingIterNext()]):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using l.extend([%s])
-l.extend([None]):TypeError:('unable to convert to vim structure',)
+l.extend([None]):TypeError:('unable to convert NoneType to vim structure',)
 l.extend([{"": 1}]):ValueError:('empty keys are not allowed',)
 l.extend([{u"": 1}]):ValueError:('empty keys are not allowed',)
 l.extend([FailingMapping()]):NotImplementedError:()
@@ -888,141 +888,141 @@
 >> ListSetattr
 del l.locked:AttributeError:('cannot delete vim.List attributes',)
 l.locked = FailingTrue():NotImplementedError:()
-l.xxx = True:AttributeError:('cannot set this attribute',)
+l.xxx = True:AttributeError:('cannot set attribute xxx',)
 > Function
 >> FunctionConstructor
-vim.Function("123"):ValueError:('unnamed function does not exist',)
-vim.Function("xxx_non_existent_function_xxx"):ValueError:('function does not exist',)
+vim.Function("123"):ValueError:('unnamed function 123 does not exist',)
+vim.Function("xxx_non_existent_function_xxx"):ValueError:('function xxx_non_existent_function_xxx does not exist',)
 vim.Function("xxx#non#existent#function#xxx"):NOT FAILED
 >> FunctionCall
 >>> Testing StringToChars using f({%s : 1})
-f({1 : 1}):TypeError:('object must be string',)
+f({1 : 1}):TypeError:('expected str() or unicode() instance, but got int',)
 f({u"\0" : 1}):TypeError:('expected string without null bytes',)
 f({"\0" : 1}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using f({"abc" : {%s : 1}})
-f({"abc" : {1 : 1}}):TypeError:('object must be string',)
+f({"abc" : {1 : 1}}):TypeError:('expected str() or unicode() instance, but got int',)
 f({"abc" : {u"\0" : 1}}):TypeError:('expected string without null bytes',)
 f({"abc" : {"\0" : 1}}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using f({"abc" : Mapping({%s : 1})})
-f({"abc" : Mapping({1 : 1})}):TypeError:('object must be string',)
+f({"abc" : Mapping({1 : 1})}):TypeError:('expected str() or unicode() instance, but got int',)
 f({"abc" : Mapping({u"\0" : 1})}):TypeError:('expected string without null bytes',)
 f({"abc" : Mapping({"\0" : 1})}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using f({"abc" : %s})
-f({"abc" : FailingIter()}):TypeError:('unable to convert to vim structure',)
+f({"abc" : FailingIter()}):TypeError:('unable to convert FailingIter to vim structure',)
 f({"abc" : FailingIterNext()}):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using f({"abc" : %s})
-f({"abc" : None}):TypeError:('unable to convert to vim structure',)
+f({"abc" : None}):TypeError:('unable to convert NoneType to vim structure',)
 f({"abc" : {"": 1}}):ValueError:('empty keys are not allowed',)
 f({"abc" : {u"": 1}}):ValueError:('empty keys are not allowed',)
 f({"abc" : FailingMapping()}):NotImplementedError:()
 f({"abc" : FailingMappingKey()}):NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using f(Mapping({%s : 1}))
-f(Mapping({1 : 1})):TypeError:('object must be string',)
+f(Mapping({1 : 1})):TypeError:('expected str() or unicode() instance, but got int',)
 f(Mapping({u"\0" : 1})):TypeError:('expected string without null bytes',)
 f(Mapping({"\0" : 1})):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using f(Mapping({"abc" : {%s : 1}}))
-f(Mapping({"abc" : {1 : 1}})):TypeError:('object must be string',)
+f(Mapping({"abc" : {1 : 1}})):TypeError:('expected str() or unicode() instance, but got int',)
 f(Mapping({"abc" : {u"\0" : 1}})):TypeError:('expected string without null bytes',)
 f(Mapping({"abc" : {"\0" : 1}})):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using f(Mapping({"abc" : Mapping({%s : 1})}))
-f(Mapping({"abc" : Mapping({1 : 1})})):TypeError:('object must be string',)
+f(Mapping({"abc" : Mapping({1 : 1})})):TypeError:('expected str() or unicode() instance, but got int',)
 f(Mapping({"abc" : Mapping({u"\0" : 1})})):TypeError:('expected string without null bytes',)
 f(Mapping({"abc" : Mapping({"\0" : 1})})):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using f(Mapping({"abc" : %s}))
-f(Mapping({"abc" : FailingIter()})):TypeError:('unable to convert to vim structure',)
+f(Mapping({"abc" : FailingIter()})):TypeError:('unable to convert FailingIter to vim structure',)
 f(Mapping({"abc" : FailingIterNext()})):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using f(Mapping({"abc" : %s}))
-f(Mapping({"abc" : None})):TypeError:('unable to convert to vim structure',)
+f(Mapping({"abc" : None})):TypeError:('unable to convert NoneType to vim structure',)
 f(Mapping({"abc" : {"": 1}})):ValueError:('empty keys are not allowed',)
 f(Mapping({"abc" : {u"": 1}})):ValueError:('empty keys are not allowed',)
 f(Mapping({"abc" : FailingMapping()})):NotImplementedError:()
 f(Mapping({"abc" : FailingMappingKey()})):NotImplementedError:()
 <<< Finished
 >>> Testing *Iter* using f(%s)
-f(FailingIter()):TypeError:('unable to convert to vim structure',)
+f(FailingIter()):TypeError:('unable to convert FailingIter to vim structure',)
 f(FailingIterNext()):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using f(%s)
-f(None):TypeError:('unable to convert to vim structure',)
+f(None):TypeError:('unable to convert NoneType to vim structure',)
 f({"": 1}):ValueError:('empty keys are not allowed',)
 f({u"": 1}):ValueError:('empty keys are not allowed',)
 f(FailingMapping()):NotImplementedError:()
 f(FailingMappingKey()):NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using fd(self={%s : 1})
-fd(self={1 : 1}):TypeError:('object must be string',)
+fd(self={1 : 1}):TypeError:('expected str() or unicode() instance, but got int',)
 fd(self={u"\0" : 1}):TypeError:('expected string without null bytes',)
 fd(self={"\0" : 1}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using fd(self={"abc" : {%s : 1}})
-fd(self={"abc" : {1 : 1}}):TypeError:('object must be string',)
+fd(self={"abc" : {1 : 1}}):TypeError:('expected str() or unicode() instance, but got int',)
 fd(self={"abc" : {u"\0" : 1}}):TypeError:('expected string without null bytes',)
 fd(self={"abc" : {"\0" : 1}}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using fd(self={"abc" : Mapping({%s : 1})})
-fd(self={"abc" : Mapping({1 : 1})}):TypeError:('object must be string',)
+fd(self={"abc" : Mapping({1 : 1})}):TypeError:('expected str() or unicode() instance, but got int',)
 fd(self={"abc" : Mapping({u"\0" : 1})}):TypeError:('expected string without null bytes',)
 fd(self={"abc" : Mapping({"\0" : 1})}):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using fd(self={"abc" : %s})
-fd(self={"abc" : FailingIter()}):TypeError:('unable to convert to vim structure',)
+fd(self={"abc" : FailingIter()}):TypeError:('unable to convert FailingIter to vim structure',)
 fd(self={"abc" : FailingIterNext()}):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using fd(self={"abc" : %s})
-fd(self={"abc" : None}):TypeError:('unable to convert to vim structure',)
+fd(self={"abc" : None}):TypeError:('unable to convert NoneType to vim structure',)
 fd(self={"abc" : {"": 1}}):ValueError:('empty keys are not allowed',)
 fd(self={"abc" : {u"": 1}}):ValueError:('empty keys are not allowed',)
 fd(self={"abc" : FailingMapping()}):NotImplementedError:()
 fd(self={"abc" : FailingMappingKey()}):NotImplementedError:()
 <<< Finished
 >>> Testing StringToChars using fd(self=Mapping({%s : 1}))
-fd(self=Mapping({1 : 1})):TypeError:('object must be string',)
+fd(self=Mapping({1 : 1})):TypeError:('expected str() or unicode() instance, but got int',)
 fd(self=Mapping({u"\0" : 1})):TypeError:('expected string without null bytes',)
 fd(self=Mapping({"\0" : 1})):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using fd(self=Mapping({"abc" : {%s : 1}}))
-fd(self=Mapping({"abc" : {1 : 1}})):TypeError:('object must be string',)
+fd(self=Mapping({"abc" : {1 : 1}})):TypeError:('expected str() or unicode() instance, but got int',)
 fd(self=Mapping({"abc" : {u"\0" : 1}})):TypeError:('expected string without null bytes',)
 fd(self=Mapping({"abc" : {"\0" : 1}})):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing StringToChars using fd(self=Mapping({"abc" : Mapping({%s : 1})}))
-fd(self=Mapping({"abc" : Mapping({1 : 1})})):TypeError:('object must be string',)
+fd(self=Mapping({"abc" : Mapping({1 : 1})})):TypeError:('expected str() or unicode() instance, but got int',)
 fd(self=Mapping({"abc" : Mapping({u"\0" : 1})})):TypeError:('expected string without null bytes',)
 fd(self=Mapping({"abc" : Mapping({"\0" : 1})})):TypeError:('expected string without null bytes',)
 <<< Finished
 >>> Testing *Iter* using fd(self=Mapping({"abc" : %s}))
-fd(self=Mapping({"abc" : FailingIter()})):TypeError:('unable to convert to vim structure',)
+fd(self=Mapping({"abc" : FailingIter()})):TypeError:('unable to convert FailingIter to vim structure',)
 fd(self=Mapping({"abc" : FailingIterNext()})):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyObject using fd(self=Mapping({"abc" : %s}))
-fd(self=Mapping({"abc" : None})):TypeError:('unable to convert to vim structure',)
+fd(self=Mapping({"abc" : None})):TypeError:('unable to convert NoneType to vim structure',)
 fd(self=Mapping({"abc" : {"": 1}})):ValueError:('empty keys are not allowed',)
 fd(self=Mapping({"abc" : {u"": 1}})):ValueError:('empty keys are not allowed',)
 fd(self=Mapping({"abc" : FailingMapping()})):NotImplementedError:()
 fd(self=Mapping({"abc" : FailingMappingKey()})):NotImplementedError:()
 <<< Finished
 >>> Testing *Iter* using fd(self=%s)
-fd(self=FailingIter()):TypeError:('unable to convert object to vim dictionary',)
-fd(self=FailingIterNext()):TypeError:('unable to convert object to vim dictionary',)
+fd(self=FailingIter()):TypeError:('unable to convert FailingIter to vim dictionary',)
+fd(self=FailingIterNext()):TypeError:('unable to convert FailingIterNext to vim dictionary',)
 <<< Finished
 >>> Testing ConvertFromPyObject using fd(self=%s)
-fd(self=None):TypeError:('unable to convert object to vim dictionary',)
+fd(self=None):TypeError:('unable to convert NoneType to vim dictionary',)
 fd(self={"": 1}):ValueError:('empty keys are not allowed',)
 fd(self={u"": 1}):ValueError:('empty keys are not allowed',)
 fd(self=FailingMapping()):NotImplementedError:()
 fd(self=FailingMappingKey()):NotImplementedError:()
 <<< Finished
 >>> Testing ConvertFromPyMapping using fd(self=%s)
-fd(self=[]):TypeError:('unable to convert object to vim dictionary',)
+fd(self=[]):TypeError:('unable to convert list to vim dictionary',)
 <<< Finished
 > TabPage
 >> TabPageAttr
@@ -1034,7 +1034,7 @@
 >> WindowAttr
 vim.current.window.xxx:AttributeError:('xxx',)
 >> WindowSetattr
-vim.current.window.buffer = 0:TypeError:('readonly attribute',)
+vim.current.window.buffer = 0:TypeError:('readonly attribute: buffer',)
 vim.current.window.cursor = (100000000, 100000000):error:('cursor position outside buffer',)
 vim.current.window.cursor = True:TypeError:('argument must be 2-item sequence, not bool',)
 vim.current.window.height = "abc":TypeError:('an integer is required',)
@@ -1062,10 +1062,10 @@
 >> BufferAttr
 vim.current.buffer.xxx:AttributeError:('xxx',)
 >> BufferSetattr
-vim.current.buffer.name = True:TypeError:('object must be string',)
+vim.current.buffer.name = True:TypeError:('expected str() or unicode() instance, but got bool',)
 vim.current.buffer.xxx = True:AttributeError:('xxx',)
 >> BufferMark
-vim.current.buffer.mark(0):TypeError:('object must be string',)
+vim.current.buffer.mark(0):TypeError:('expected str() or unicode() instance, but got int',)
 vim.current.buffer.mark("abc"):ValueError:('mark name must be a single character',)
 vim.current.buffer.mark("!"):error:('invalid mark name',)
 >> BufferRange
@@ -1079,9 +1079,9 @@
 vim.current.xxx:AttributeError:('xxx',)
 >> CurrentSetattr
 vim.current.line = True:TypeError:('bad argument type for built-in operation',)
-vim.current.buffer = True:TypeError:('expected vim.Buffer object',)
-vim.current.window = True:TypeError:('expected vim.Window object',)
-vim.current.tabpage = True:TypeError:('expected vim.TabPage object',)
+vim.current.buffer = True:TypeError:('expected vim.Buffer object, but got bool',)
+vim.current.window = True:TypeError:('expected vim.Window object, but got bool',)
+vim.current.tabpage = True:TypeError:('expected vim.TabPage object, but got bool',)
 vim.current.xxx = True:AttributeError:('xxx',)
 2,xx
 before
diff --git a/src/testdir/test87.ok b/src/testdir/test87.ok
index 7ee1a1c..4b73034 100644
--- a/src/testdir/test87.ok
+++ b/src/testdir/test87.ok
@@ -428,7 +428,7 @@
 >> OutputSetattr
 del sys.stdout.softspace:(<class 'AttributeError'>, AttributeError("can't delete OutputObject attributes",))
 sys.stdout.softspace = []:(<class 'TypeError'>, TypeError('softspace must be an integer',))
-sys.stdout.attr = None:(<class 'AttributeError'>, AttributeError('invalid attribute',))
+sys.stdout.attr = None:(<class 'AttributeError'>, AttributeError('invalid attribute: attr',))
 >> OutputWrite
 sys.stdout.write(None):(<class 'TypeError'>, TypeError("Can't convert 'NoneType' object to str implicitly",))
 >> OutputWriteLines
@@ -439,99 +439,99 @@
 sys.stdout.writelines(FailingIterNext()):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 > VimCommand
-vim.command(1):(<class 'TypeError'>, TypeError('object must be string',))
+vim.command(1):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 > VimToPython
 > VimEval
-vim.eval(1):(<class 'TypeError'>, TypeError('object must be string',))
+vim.eval(1):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 > VimEvalPy
-vim.bindeval(1):(<class 'TypeError'>, TypeError('object must be string',))
+vim.bindeval(1):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 > VimStrwidth
-vim.strwidth(1):(<class 'TypeError'>, TypeError('object must be string',))
+vim.strwidth(1):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 > Dictionary
 >> DictionaryConstructor
-vim.Dictionary("abc"):(<class 'ValueError'>, ValueError('expected sequence element of size 2',))
+vim.Dictionary("abc"):(<class 'ValueError'>, ValueError('expected sequence element of size 2, but got sequence of size 1',))
 >> DictionarySetattr
 del d.locked:(<class 'AttributeError'>, AttributeError('cannot delete vim.Dictionary attributes',))
 d.locked = FailingTrue():(<class 'NotImplementedError'>, NotImplementedError())
 vim.vvars.locked = False:(<class 'TypeError'>, TypeError('cannot modify fixed dictionary',))
-d.scope = True:(<class 'AttributeError'>, AttributeError('cannot set this attribute',))
-d.xxx = True:(<class 'AttributeError'>, AttributeError('cannot set this attribute',))
+d.scope = True:(<class 'AttributeError'>, AttributeError('cannot set attribute scope',))
+d.xxx = True:(<class 'AttributeError'>, AttributeError('cannot set attribute xxx',))
 >> _DictionaryItem
 d.get("a", 2, 3):(<class 'TypeError'>, TypeError('function takes at most 2 arguments (3 given)',))
 >>> Testing StringToChars using d.get(%s)
-d.get(1):(<class 'TypeError'>, TypeError('object must be string',))
+d.get(1):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.get(b"\0"):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.get("\0"):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 d.pop("a"):(<class 'KeyError'>, KeyError('a',))
-dl.pop("a"):(<class 'vim.error'>, error('dict is locked',))
+dl.pop("a"):(<class 'vim.error'>, error('dictionary is locked',))
 >> DictionaryIterNext
 for i in ned: ned["a"] = 1:(<class 'RuntimeError'>, RuntimeError('hashtab changed during iteration',))
 >> DictionaryAssItem
-dl["b"] = 1:(<class 'vim.error'>, error('dict is locked',))
+dl["b"] = 1:(<class 'vim.error'>, error('dictionary is locked',))
 >>> Testing StringToChars using d[%s] = 1
-d[1] = 1:(<class 'TypeError'>, TypeError('object must be string',))
+d[1] = 1:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d[b"\0"] = 1:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d["\0"] = 1:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d["a"] = {%s : 1}
-d["a"] = {1 : 1}:(<class 'TypeError'>, TypeError('object must be string',))
+d["a"] = {1 : 1}:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d["a"] = {b"\0" : 1}:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d["a"] = {"\0" : 1}:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d["a"] = {"abc" : {%s : 1}}
-d["a"] = {"abc" : {1 : 1}}:(<class 'TypeError'>, TypeError('object must be string',))
+d["a"] = {"abc" : {1 : 1}}:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d["a"] = {"abc" : {b"\0" : 1}}:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d["a"] = {"abc" : {"\0" : 1}}:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d["a"] = {"abc" : Mapping({%s : 1})}
-d["a"] = {"abc" : Mapping({1 : 1})}:(<class 'TypeError'>, TypeError('object must be string',))
+d["a"] = {"abc" : Mapping({1 : 1})}:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d["a"] = {"abc" : Mapping({b"\0" : 1})}:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d["a"] = {"abc" : Mapping({"\0" : 1})}:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using d["a"] = {"abc" : %s}
-d["a"] = {"abc" : FailingIter()}:(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d["a"] = {"abc" : FailingIter()}:(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 d["a"] = {"abc" : FailingIterNext()}:(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using d["a"] = {"abc" : %s}
-d["a"] = {"abc" : None}:(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d["a"] = {"abc" : None}:(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 d["a"] = {"abc" : {b"": 1}}:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d["a"] = {"abc" : {"": 1}}:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d["a"] = {"abc" : FailingMapping()}:(<class 'NotImplementedError'>, NotImplementedError())
 d["a"] = {"abc" : FailingMappingKey()}:(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using d["a"] = Mapping({%s : 1})
-d["a"] = Mapping({1 : 1}):(<class 'TypeError'>, TypeError('object must be string',))
+d["a"] = Mapping({1 : 1}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d["a"] = Mapping({b"\0" : 1}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d["a"] = Mapping({"\0" : 1}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d["a"] = Mapping({"abc" : {%s : 1}})
-d["a"] = Mapping({"abc" : {1 : 1}}):(<class 'TypeError'>, TypeError('object must be string',))
+d["a"] = Mapping({"abc" : {1 : 1}}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d["a"] = Mapping({"abc" : {b"\0" : 1}}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d["a"] = Mapping({"abc" : {"\0" : 1}}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d["a"] = Mapping({"abc" : Mapping({%s : 1})})
-d["a"] = Mapping({"abc" : Mapping({1 : 1})}):(<class 'TypeError'>, TypeError('object must be string',))
+d["a"] = Mapping({"abc" : Mapping({1 : 1})}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d["a"] = Mapping({"abc" : Mapping({b"\0" : 1})}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d["a"] = Mapping({"abc" : Mapping({"\0" : 1})}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using d["a"] = Mapping({"abc" : %s})
-d["a"] = Mapping({"abc" : FailingIter()}):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d["a"] = Mapping({"abc" : FailingIter()}):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 d["a"] = Mapping({"abc" : FailingIterNext()}):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using d["a"] = Mapping({"abc" : %s})
-d["a"] = Mapping({"abc" : None}):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d["a"] = Mapping({"abc" : None}):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 d["a"] = Mapping({"abc" : {b"": 1}}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d["a"] = Mapping({"abc" : {"": 1}}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d["a"] = Mapping({"abc" : FailingMapping()}):(<class 'NotImplementedError'>, NotImplementedError())
 d["a"] = Mapping({"abc" : FailingMappingKey()}):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing *Iter* using d["a"] = %s
-d["a"] = FailingIter():(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d["a"] = FailingIter():(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 d["a"] = FailingIterNext():(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using d["a"] = %s
-d["a"] = None:(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d["a"] = None:(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 d["a"] = {b"": 1}:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d["a"] = {"": 1}:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d["a"] = FailingMapping():(<class 'NotImplementedError'>, NotImplementedError())
@@ -547,52 +547,52 @@
 d.update(FailingIterNext()):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using d.update({%s : 1})
-d.update({1 : 1}):(<class 'TypeError'>, TypeError('object must be string',))
+d.update({1 : 1}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update({b"\0" : 1}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update({"\0" : 1}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d.update({"abc" : {%s : 1}})
-d.update({"abc" : {1 : 1}}):(<class 'TypeError'>, TypeError('object must be string',))
+d.update({"abc" : {1 : 1}}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update({"abc" : {b"\0" : 1}}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update({"abc" : {"\0" : 1}}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d.update({"abc" : Mapping({%s : 1})})
-d.update({"abc" : Mapping({1 : 1})}):(<class 'TypeError'>, TypeError('object must be string',))
+d.update({"abc" : Mapping({1 : 1})}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update({"abc" : Mapping({b"\0" : 1})}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update({"abc" : Mapping({"\0" : 1})}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using d.update({"abc" : %s})
-d.update({"abc" : FailingIter()}):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update({"abc" : FailingIter()}):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 d.update({"abc" : FailingIterNext()}):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update({"abc" : %s})
-d.update({"abc" : None}):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update({"abc" : None}):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 d.update({"abc" : {b"": 1}}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update({"abc" : {"": 1}}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update({"abc" : FailingMapping()}):(<class 'NotImplementedError'>, NotImplementedError())
 d.update({"abc" : FailingMappingKey()}):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using d.update(Mapping({%s : 1}))
-d.update(Mapping({1 : 1})):(<class 'TypeError'>, TypeError('object must be string',))
+d.update(Mapping({1 : 1})):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update(Mapping({b"\0" : 1})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update(Mapping({"\0" : 1})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d.update(Mapping({"abc" : {%s : 1}}))
-d.update(Mapping({"abc" : {1 : 1}})):(<class 'TypeError'>, TypeError('object must be string',))
+d.update(Mapping({"abc" : {1 : 1}})):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update(Mapping({"abc" : {b"\0" : 1}})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update(Mapping({"abc" : {"\0" : 1}})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d.update(Mapping({"abc" : Mapping({%s : 1})}))
-d.update(Mapping({"abc" : Mapping({1 : 1})})):(<class 'TypeError'>, TypeError('object must be string',))
+d.update(Mapping({"abc" : Mapping({1 : 1})})):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update(Mapping({"abc" : Mapping({b"\0" : 1})})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update(Mapping({"abc" : Mapping({"\0" : 1})})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using d.update(Mapping({"abc" : %s}))
-d.update(Mapping({"abc" : FailingIter()})):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update(Mapping({"abc" : FailingIter()})):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 d.update(Mapping({"abc" : FailingIterNext()})):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update(Mapping({"abc" : %s}))
-d.update(Mapping({"abc" : None})):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update(Mapping({"abc" : None})):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 d.update(Mapping({"abc" : {b"": 1}})):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update(Mapping({"abc" : {"": 1}})):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update(Mapping({"abc" : FailingMapping()})):(<class 'NotImplementedError'>, NotImplementedError())
@@ -610,68 +610,68 @@
 d.update(FailingMappingKey()):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using d.update(((%s, 0),))
-d.update(((1, 0),)):(<class 'TypeError'>, TypeError('object must be string',))
+d.update(((1, 0),)):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update(((b"\0", 0),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update((("\0", 0),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d.update((("a", {%s : 1}),))
-d.update((("a", {1 : 1}),)):(<class 'TypeError'>, TypeError('object must be string',))
+d.update((("a", {1 : 1}),)):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update((("a", {b"\0" : 1}),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update((("a", {"\0" : 1}),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d.update((("a", {"abc" : {%s : 1}}),))
-d.update((("a", {"abc" : {1 : 1}}),)):(<class 'TypeError'>, TypeError('object must be string',))
+d.update((("a", {"abc" : {1 : 1}}),)):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update((("a", {"abc" : {b"\0" : 1}}),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update((("a", {"abc" : {"\0" : 1}}),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d.update((("a", {"abc" : Mapping({%s : 1})}),))
-d.update((("a", {"abc" : Mapping({1 : 1})}),)):(<class 'TypeError'>, TypeError('object must be string',))
+d.update((("a", {"abc" : Mapping({1 : 1})}),)):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update((("a", {"abc" : Mapping({b"\0" : 1})}),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update((("a", {"abc" : Mapping({"\0" : 1})}),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using d.update((("a", {"abc" : %s}),))
-d.update((("a", {"abc" : FailingIter()}),)):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update((("a", {"abc" : FailingIter()}),)):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 d.update((("a", {"abc" : FailingIterNext()}),)):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update((("a", {"abc" : %s}),))
-d.update((("a", {"abc" : None}),)):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update((("a", {"abc" : None}),)):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 d.update((("a", {"abc" : {b"": 1}}),)):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update((("a", {"abc" : {"": 1}}),)):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update((("a", {"abc" : FailingMapping()}),)):(<class 'NotImplementedError'>, NotImplementedError())
 d.update((("a", {"abc" : FailingMappingKey()}),)):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using d.update((("a", Mapping({%s : 1})),))
-d.update((("a", Mapping({1 : 1})),)):(<class 'TypeError'>, TypeError('object must be string',))
+d.update((("a", Mapping({1 : 1})),)):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update((("a", Mapping({b"\0" : 1})),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update((("a", Mapping({"\0" : 1})),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d.update((("a", Mapping({"abc" : {%s : 1}})),))
-d.update((("a", Mapping({"abc" : {1 : 1}})),)):(<class 'TypeError'>, TypeError('object must be string',))
+d.update((("a", Mapping({"abc" : {1 : 1}})),)):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update((("a", Mapping({"abc" : {b"\0" : 1}})),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update((("a", Mapping({"abc" : {"\0" : 1}})),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using d.update((("a", Mapping({"abc" : Mapping({%s : 1})})),))
-d.update((("a", Mapping({"abc" : Mapping({1 : 1})})),)):(<class 'TypeError'>, TypeError('object must be string',))
+d.update((("a", Mapping({"abc" : Mapping({1 : 1})})),)):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 d.update((("a", Mapping({"abc" : Mapping({b"\0" : 1})})),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 d.update((("a", Mapping({"abc" : Mapping({"\0" : 1})})),)):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using d.update((("a", Mapping({"abc" : %s})),))
-d.update((("a", Mapping({"abc" : FailingIter()})),)):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update((("a", Mapping({"abc" : FailingIter()})),)):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 d.update((("a", Mapping({"abc" : FailingIterNext()})),)):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update((("a", Mapping({"abc" : %s})),))
-d.update((("a", Mapping({"abc" : None})),)):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update((("a", Mapping({"abc" : None})),)):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 d.update((("a", Mapping({"abc" : {b"": 1}})),)):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update((("a", Mapping({"abc" : {"": 1}})),)):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update((("a", Mapping({"abc" : FailingMapping()})),)):(<class 'NotImplementedError'>, NotImplementedError())
 d.update((("a", Mapping({"abc" : FailingMappingKey()})),)):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing *Iter* using d.update((("a", %s),))
-d.update((("a", FailingIter()),)):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update((("a", FailingIter()),)):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 d.update((("a", FailingIterNext()),)):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using d.update((("a", %s),))
-d.update((("a", None),)):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+d.update((("a", None),)):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 d.update((("a", {b"": 1}),)):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update((("a", {"": 1}),)):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 d.update((("a", FailingMapping()),)):(<class 'NotImplementedError'>, NotImplementedError())
@@ -690,63 +690,63 @@
 vim.List(FailingIterNext()):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using vim.List([{%s : 1}])
-vim.List([{1 : 1}]):(<class 'TypeError'>, TypeError('object must be string',))
+vim.List([{1 : 1}]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 vim.List([{b"\0" : 1}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 vim.List([{"\0" : 1}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using vim.List([{"abc" : {%s : 1}}])
-vim.List([{"abc" : {1 : 1}}]):(<class 'TypeError'>, TypeError('object must be string',))
+vim.List([{"abc" : {1 : 1}}]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 vim.List([{"abc" : {b"\0" : 1}}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 vim.List([{"abc" : {"\0" : 1}}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using vim.List([{"abc" : Mapping({%s : 1})}])
-vim.List([{"abc" : Mapping({1 : 1})}]):(<class 'TypeError'>, TypeError('object must be string',))
+vim.List([{"abc" : Mapping({1 : 1})}]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 vim.List([{"abc" : Mapping({b"\0" : 1})}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 vim.List([{"abc" : Mapping({"\0" : 1})}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using vim.List([{"abc" : %s}])
-vim.List([{"abc" : FailingIter()}]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+vim.List([{"abc" : FailingIter()}]):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 vim.List([{"abc" : FailingIterNext()}]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using vim.List([{"abc" : %s}])
-vim.List([{"abc" : None}]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+vim.List([{"abc" : None}]):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 vim.List([{"abc" : {b"": 1}}]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 vim.List([{"abc" : {"": 1}}]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 vim.List([{"abc" : FailingMapping()}]):(<class 'NotImplementedError'>, NotImplementedError())
 vim.List([{"abc" : FailingMappingKey()}]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using vim.List([Mapping({%s : 1})])
-vim.List([Mapping({1 : 1})]):(<class 'TypeError'>, TypeError('object must be string',))
+vim.List([Mapping({1 : 1})]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 vim.List([Mapping({b"\0" : 1})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 vim.List([Mapping({"\0" : 1})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using vim.List([Mapping({"abc" : {%s : 1}})])
-vim.List([Mapping({"abc" : {1 : 1}})]):(<class 'TypeError'>, TypeError('object must be string',))
+vim.List([Mapping({"abc" : {1 : 1}})]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 vim.List([Mapping({"abc" : {b"\0" : 1}})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 vim.List([Mapping({"abc" : {"\0" : 1}})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using vim.List([Mapping({"abc" : Mapping({%s : 1})})])
-vim.List([Mapping({"abc" : Mapping({1 : 1})})]):(<class 'TypeError'>, TypeError('object must be string',))
+vim.List([Mapping({"abc" : Mapping({1 : 1})})]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 vim.List([Mapping({"abc" : Mapping({b"\0" : 1})})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 vim.List([Mapping({"abc" : Mapping({"\0" : 1})})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using vim.List([Mapping({"abc" : %s})])
-vim.List([Mapping({"abc" : FailingIter()})]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+vim.List([Mapping({"abc" : FailingIter()})]):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 vim.List([Mapping({"abc" : FailingIterNext()})]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using vim.List([Mapping({"abc" : %s})])
-vim.List([Mapping({"abc" : None})]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+vim.List([Mapping({"abc" : None})]):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 vim.List([Mapping({"abc" : {b"": 1}})]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 vim.List([Mapping({"abc" : {"": 1}})]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 vim.List([Mapping({"abc" : FailingMapping()})]):(<class 'NotImplementedError'>, NotImplementedError())
 vim.List([Mapping({"abc" : FailingMappingKey()})]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing *Iter* using vim.List([%s])
-vim.List([FailingIter()]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+vim.List([FailingIter()]):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 vim.List([FailingIterNext()]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using vim.List([%s])
-vim.List([None]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+vim.List([None]):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 vim.List([{b"": 1}]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 vim.List([{"": 1}]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 vim.List([FailingMapping()]):(<class 'NotImplementedError'>, NotImplementedError())
@@ -764,63 +764,63 @@
 l[:] = FailingIterNext()::(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using l[:] = [{%s : 1}]
-l[:] = [{1 : 1}]:(<class 'TypeError'>, TypeError('object must be string',))
+l[:] = [{1 : 1}]:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l[:] = [{b"\0" : 1}]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l[:] = [{"\0" : 1}]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using l[:] = [{"abc" : {%s : 1}}]
-l[:] = [{"abc" : {1 : 1}}]:(<class 'TypeError'>, TypeError('object must be string',))
+l[:] = [{"abc" : {1 : 1}}]:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l[:] = [{"abc" : {b"\0" : 1}}]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l[:] = [{"abc" : {"\0" : 1}}]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using l[:] = [{"abc" : Mapping({%s : 1})}]
-l[:] = [{"abc" : Mapping({1 : 1})}]:(<class 'TypeError'>, TypeError('object must be string',))
+l[:] = [{"abc" : Mapping({1 : 1})}]:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l[:] = [{"abc" : Mapping({b"\0" : 1})}]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l[:] = [{"abc" : Mapping({"\0" : 1})}]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using l[:] = [{"abc" : %s}]
-l[:] = [{"abc" : FailingIter()}]:(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l[:] = [{"abc" : FailingIter()}]:(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 l[:] = [{"abc" : FailingIterNext()}]:(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using l[:] = [{"abc" : %s}]
-l[:] = [{"abc" : None}]:(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l[:] = [{"abc" : None}]:(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 l[:] = [{"abc" : {b"": 1}}]:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l[:] = [{"abc" : {"": 1}}]:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l[:] = [{"abc" : FailingMapping()}]:(<class 'NotImplementedError'>, NotImplementedError())
 l[:] = [{"abc" : FailingMappingKey()}]:(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using l[:] = [Mapping({%s : 1})]
-l[:] = [Mapping({1 : 1})]:(<class 'TypeError'>, TypeError('object must be string',))
+l[:] = [Mapping({1 : 1})]:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l[:] = [Mapping({b"\0" : 1})]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l[:] = [Mapping({"\0" : 1})]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using l[:] = [Mapping({"abc" : {%s : 1}})]
-l[:] = [Mapping({"abc" : {1 : 1}})]:(<class 'TypeError'>, TypeError('object must be string',))
+l[:] = [Mapping({"abc" : {1 : 1}})]:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l[:] = [Mapping({"abc" : {b"\0" : 1}})]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l[:] = [Mapping({"abc" : {"\0" : 1}})]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using l[:] = [Mapping({"abc" : Mapping({%s : 1})})]
-l[:] = [Mapping({"abc" : Mapping({1 : 1})})]:(<class 'TypeError'>, TypeError('object must be string',))
+l[:] = [Mapping({"abc" : Mapping({1 : 1})})]:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l[:] = [Mapping({"abc" : Mapping({b"\0" : 1})})]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l[:] = [Mapping({"abc" : Mapping({"\0" : 1})})]:(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using l[:] = [Mapping({"abc" : %s})]
-l[:] = [Mapping({"abc" : FailingIter()})]:(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l[:] = [Mapping({"abc" : FailingIter()})]:(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 l[:] = [Mapping({"abc" : FailingIterNext()})]:(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using l[:] = [Mapping({"abc" : %s})]
-l[:] = [Mapping({"abc" : None})]:(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l[:] = [Mapping({"abc" : None})]:(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 l[:] = [Mapping({"abc" : {b"": 1}})]:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l[:] = [Mapping({"abc" : {"": 1}})]:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l[:] = [Mapping({"abc" : FailingMapping()})]:(<class 'NotImplementedError'>, NotImplementedError())
 l[:] = [Mapping({"abc" : FailingMappingKey()})]:(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing *Iter* using l[:] = [%s]
-l[:] = [FailingIter()]:(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l[:] = [FailingIter()]:(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 l[:] = [FailingIterNext()]:(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using l[:] = [%s]
-l[:] = [None]:(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l[:] = [None]:(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 l[:] = [{b"": 1}]:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l[:] = [{"": 1}]:(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l[:] = [FailingMapping()]:(<class 'NotImplementedError'>, NotImplementedError())
@@ -832,63 +832,63 @@
 l.extend(FailingIterNext()):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using l.extend([{%s : 1}])
-l.extend([{1 : 1}]):(<class 'TypeError'>, TypeError('object must be string',))
+l.extend([{1 : 1}]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l.extend([{b"\0" : 1}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l.extend([{"\0" : 1}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using l.extend([{"abc" : {%s : 1}}])
-l.extend([{"abc" : {1 : 1}}]):(<class 'TypeError'>, TypeError('object must be string',))
+l.extend([{"abc" : {1 : 1}}]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l.extend([{"abc" : {b"\0" : 1}}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l.extend([{"abc" : {"\0" : 1}}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using l.extend([{"abc" : Mapping({%s : 1})}])
-l.extend([{"abc" : Mapping({1 : 1})}]):(<class 'TypeError'>, TypeError('object must be string',))
+l.extend([{"abc" : Mapping({1 : 1})}]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l.extend([{"abc" : Mapping({b"\0" : 1})}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l.extend([{"abc" : Mapping({"\0" : 1})}]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using l.extend([{"abc" : %s}])
-l.extend([{"abc" : FailingIter()}]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l.extend([{"abc" : FailingIter()}]):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 l.extend([{"abc" : FailingIterNext()}]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using l.extend([{"abc" : %s}])
-l.extend([{"abc" : None}]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l.extend([{"abc" : None}]):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 l.extend([{"abc" : {b"": 1}}]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l.extend([{"abc" : {"": 1}}]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l.extend([{"abc" : FailingMapping()}]):(<class 'NotImplementedError'>, NotImplementedError())
 l.extend([{"abc" : FailingMappingKey()}]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using l.extend([Mapping({%s : 1})])
-l.extend([Mapping({1 : 1})]):(<class 'TypeError'>, TypeError('object must be string',))
+l.extend([Mapping({1 : 1})]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l.extend([Mapping({b"\0" : 1})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l.extend([Mapping({"\0" : 1})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using l.extend([Mapping({"abc" : {%s : 1}})])
-l.extend([Mapping({"abc" : {1 : 1}})]):(<class 'TypeError'>, TypeError('object must be string',))
+l.extend([Mapping({"abc" : {1 : 1}})]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l.extend([Mapping({"abc" : {b"\0" : 1}})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l.extend([Mapping({"abc" : {"\0" : 1}})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using l.extend([Mapping({"abc" : Mapping({%s : 1})})])
-l.extend([Mapping({"abc" : Mapping({1 : 1})})]):(<class 'TypeError'>, TypeError('object must be string',))
+l.extend([Mapping({"abc" : Mapping({1 : 1})})]):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 l.extend([Mapping({"abc" : Mapping({b"\0" : 1})})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 l.extend([Mapping({"abc" : Mapping({"\0" : 1})})]):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using l.extend([Mapping({"abc" : %s})])
-l.extend([Mapping({"abc" : FailingIter()})]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l.extend([Mapping({"abc" : FailingIter()})]):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 l.extend([Mapping({"abc" : FailingIterNext()})]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using l.extend([Mapping({"abc" : %s})])
-l.extend([Mapping({"abc" : None})]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l.extend([Mapping({"abc" : None})]):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 l.extend([Mapping({"abc" : {b"": 1}})]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l.extend([Mapping({"abc" : {"": 1}})]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l.extend([Mapping({"abc" : FailingMapping()})]):(<class 'NotImplementedError'>, NotImplementedError())
 l.extend([Mapping({"abc" : FailingMappingKey()})]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing *Iter* using l.extend([%s])
-l.extend([FailingIter()]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l.extend([FailingIter()]):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 l.extend([FailingIterNext()]):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using l.extend([%s])
-l.extend([None]):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+l.extend([None]):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 l.extend([{b"": 1}]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l.extend([{"": 1}]):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 l.extend([FailingMapping()]):(<class 'NotImplementedError'>, NotImplementedError())
@@ -897,134 +897,134 @@
 >> ListSetattr
 del l.locked:(<class 'AttributeError'>, AttributeError('cannot delete vim.List attributes',))
 l.locked = FailingTrue():(<class 'NotImplementedError'>, NotImplementedError())
-l.xxx = True:(<class 'AttributeError'>, AttributeError('cannot set this attribute',))
+l.xxx = True:(<class 'AttributeError'>, AttributeError('cannot set attribute xxx',))
 > Function
 >> FunctionConstructor
-vim.Function("123"):(<class 'ValueError'>, ValueError('unnamed function does not exist',))
-vim.Function("xxx_non_existent_function_xxx"):(<class 'ValueError'>, ValueError('function does not exist',))
+vim.Function("123"):(<class 'ValueError'>, ValueError('unnamed function 123 does not exist',))
+vim.Function("xxx_non_existent_function_xxx"):(<class 'ValueError'>, ValueError('function xxx_non_existent_function_xxx does not exist',))
 vim.Function("xxx#non#existent#function#xxx"):NOT FAILED
 >> FunctionCall
 >>> Testing StringToChars using f({%s : 1})
-f({1 : 1}):(<class 'TypeError'>, TypeError('object must be string',))
+f({1 : 1}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 f({b"\0" : 1}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 f({"\0" : 1}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using f({"abc" : {%s : 1}})
-f({"abc" : {1 : 1}}):(<class 'TypeError'>, TypeError('object must be string',))
+f({"abc" : {1 : 1}}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 f({"abc" : {b"\0" : 1}}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 f({"abc" : {"\0" : 1}}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using f({"abc" : Mapping({%s : 1})})
-f({"abc" : Mapping({1 : 1})}):(<class 'TypeError'>, TypeError('object must be string',))
+f({"abc" : Mapping({1 : 1})}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 f({"abc" : Mapping({b"\0" : 1})}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 f({"abc" : Mapping({"\0" : 1})}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using f({"abc" : %s})
-f({"abc" : FailingIter()}):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+f({"abc" : FailingIter()}):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 f({"abc" : FailingIterNext()}):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using f({"abc" : %s})
-f({"abc" : None}):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+f({"abc" : None}):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 f({"abc" : {b"": 1}}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 f({"abc" : {"": 1}}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 f({"abc" : FailingMapping()}):(<class 'NotImplementedError'>, NotImplementedError())
 f({"abc" : FailingMappingKey()}):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using f(Mapping({%s : 1}))
-f(Mapping({1 : 1})):(<class 'TypeError'>, TypeError('object must be string',))
+f(Mapping({1 : 1})):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 f(Mapping({b"\0" : 1})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 f(Mapping({"\0" : 1})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using f(Mapping({"abc" : {%s : 1}}))
-f(Mapping({"abc" : {1 : 1}})):(<class 'TypeError'>, TypeError('object must be string',))
+f(Mapping({"abc" : {1 : 1}})):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 f(Mapping({"abc" : {b"\0" : 1}})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 f(Mapping({"abc" : {"\0" : 1}})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using f(Mapping({"abc" : Mapping({%s : 1})}))
-f(Mapping({"abc" : Mapping({1 : 1})})):(<class 'TypeError'>, TypeError('object must be string',))
+f(Mapping({"abc" : Mapping({1 : 1})})):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 f(Mapping({"abc" : Mapping({b"\0" : 1})})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 f(Mapping({"abc" : Mapping({"\0" : 1})})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using f(Mapping({"abc" : %s}))
-f(Mapping({"abc" : FailingIter()})):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+f(Mapping({"abc" : FailingIter()})):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 f(Mapping({"abc" : FailingIterNext()})):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using f(Mapping({"abc" : %s}))
-f(Mapping({"abc" : None})):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+f(Mapping({"abc" : None})):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 f(Mapping({"abc" : {b"": 1}})):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 f(Mapping({"abc" : {"": 1}})):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 f(Mapping({"abc" : FailingMapping()})):(<class 'NotImplementedError'>, NotImplementedError())
 f(Mapping({"abc" : FailingMappingKey()})):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing *Iter* using f(%s)
-f(FailingIter()):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+f(FailingIter()):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 f(FailingIterNext()):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using f(%s)
-f(None):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+f(None):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 f({b"": 1}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 f({"": 1}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 f(FailingMapping()):(<class 'NotImplementedError'>, NotImplementedError())
 f(FailingMappingKey()):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using fd(self={%s : 1})
-fd(self={1 : 1}):(<class 'TypeError'>, TypeError('object must be string',))
+fd(self={1 : 1}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 fd(self={b"\0" : 1}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 fd(self={"\0" : 1}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using fd(self={"abc" : {%s : 1}})
-fd(self={"abc" : {1 : 1}}):(<class 'TypeError'>, TypeError('object must be string',))
+fd(self={"abc" : {1 : 1}}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 fd(self={"abc" : {b"\0" : 1}}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 fd(self={"abc" : {"\0" : 1}}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using fd(self={"abc" : Mapping({%s : 1})})
-fd(self={"abc" : Mapping({1 : 1})}):(<class 'TypeError'>, TypeError('object must be string',))
+fd(self={"abc" : Mapping({1 : 1})}):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 fd(self={"abc" : Mapping({b"\0" : 1})}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 fd(self={"abc" : Mapping({"\0" : 1})}):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using fd(self={"abc" : %s})
-fd(self={"abc" : FailingIter()}):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+fd(self={"abc" : FailingIter()}):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 fd(self={"abc" : FailingIterNext()}):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using fd(self={"abc" : %s})
-fd(self={"abc" : None}):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+fd(self={"abc" : None}):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 fd(self={"abc" : {b"": 1}}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 fd(self={"abc" : {"": 1}}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 fd(self={"abc" : FailingMapping()}):(<class 'NotImplementedError'>, NotImplementedError())
 fd(self={"abc" : FailingMappingKey()}):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing StringToChars using fd(self=Mapping({%s : 1}))
-fd(self=Mapping({1 : 1})):(<class 'TypeError'>, TypeError('object must be string',))
+fd(self=Mapping({1 : 1})):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 fd(self=Mapping({b"\0" : 1})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 fd(self=Mapping({"\0" : 1})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using fd(self=Mapping({"abc" : {%s : 1}}))
-fd(self=Mapping({"abc" : {1 : 1}})):(<class 'TypeError'>, TypeError('object must be string',))
+fd(self=Mapping({"abc" : {1 : 1}})):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 fd(self=Mapping({"abc" : {b"\0" : 1}})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 fd(self=Mapping({"abc" : {"\0" : 1}})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing StringToChars using fd(self=Mapping({"abc" : Mapping({%s : 1})}))
-fd(self=Mapping({"abc" : Mapping({1 : 1})})):(<class 'TypeError'>, TypeError('object must be string',))
+fd(self=Mapping({"abc" : Mapping({1 : 1})})):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 fd(self=Mapping({"abc" : Mapping({b"\0" : 1})})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 fd(self=Mapping({"abc" : Mapping({"\0" : 1})})):(<class 'TypeError'>, TypeError('expected bytes with no null',))
 <<< Finished
 >>> Testing *Iter* using fd(self=Mapping({"abc" : %s}))
-fd(self=Mapping({"abc" : FailingIter()})):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+fd(self=Mapping({"abc" : FailingIter()})):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim structure',))
 fd(self=Mapping({"abc" : FailingIterNext()})):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing ConvertFromPyObject using fd(self=Mapping({"abc" : %s}))
-fd(self=Mapping({"abc" : None})):(<class 'TypeError'>, TypeError('unable to convert to vim structure',))
+fd(self=Mapping({"abc" : None})):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim structure',))
 fd(self=Mapping({"abc" : {b"": 1}})):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 fd(self=Mapping({"abc" : {"": 1}})):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 fd(self=Mapping({"abc" : FailingMapping()})):(<class 'NotImplementedError'>, NotImplementedError())
 fd(self=Mapping({"abc" : FailingMappingKey()})):(<class 'NotImplementedError'>, NotImplementedError())
 <<< Finished
 >>> Testing *Iter* using fd(self=%s)
-fd(self=FailingIter()):(<class 'TypeError'>, TypeError('unable to convert object to vim dictionary',))
-fd(self=FailingIterNext()):(<class 'TypeError'>, TypeError('unable to convert object to vim dictionary',))
+fd(self=FailingIter()):(<class 'TypeError'>, TypeError('unable to convert FailingIter to vim dictionary',))
+fd(self=FailingIterNext()):(<class 'TypeError'>, TypeError('unable to convert FailingIterNext to vim dictionary',))
 <<< Finished
 >>> Testing ConvertFromPyObject using fd(self=%s)
-fd(self=None):(<class 'TypeError'>, TypeError('unable to convert object to vim dictionary',))
+fd(self=None):(<class 'TypeError'>, TypeError('unable to convert NoneType to vim dictionary',))
 fd(self={b"": 1}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 fd(self={"": 1}):(<class 'ValueError'>, ValueError('empty keys are not allowed',))
 fd(self=FailingMapping()):(<class 'NotImplementedError'>, NotImplementedError())
@@ -1043,7 +1043,7 @@
 >> WindowAttr
 vim.current.window.xxx:(<class 'AttributeError'>, AttributeError("'vim.window' object has no attribute 'xxx'",))
 >> WindowSetattr
-vim.current.window.buffer = 0:(<class 'TypeError'>, TypeError('readonly attribute',))
+vim.current.window.buffer = 0:(<class 'TypeError'>, TypeError('readonly attribute: buffer',))
 vim.current.window.cursor = (100000000, 100000000):(<class 'vim.error'>, error('cursor position outside buffer',))
 vim.current.window.cursor = True:(<class 'TypeError'>, TypeError('argument must be 2-item sequence, not bool',))
 vim.current.window.height = "abc":(<class 'TypeError'>, TypeError('an integer is required',))
@@ -1071,10 +1071,10 @@
 >> BufferAttr
 vim.current.buffer.xxx:(<class 'AttributeError'>, AttributeError("'vim.buffer' object has no attribute 'xxx'",))
 >> BufferSetattr
-vim.current.buffer.name = True:(<class 'TypeError'>, TypeError('object must be string',))
+vim.current.buffer.name = True:(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got bool',))
 vim.current.buffer.xxx = True:(<class 'AttributeError'>, AttributeError('xxx',))
 >> BufferMark
-vim.current.buffer.mark(0):(<class 'TypeError'>, TypeError('object must be string',))
+vim.current.buffer.mark(0):(<class 'TypeError'>, TypeError('expected bytes() or str() instance, but got int',))
 vim.current.buffer.mark("abc"):(<class 'ValueError'>, ValueError('mark name must be a single character',))
 vim.current.buffer.mark("!"):(<class 'vim.error'>, error('invalid mark name',))
 >> BufferRange
@@ -1088,9 +1088,9 @@
 vim.current.xxx:(<class 'AttributeError'>, AttributeError("'vim.currentdata' object has no attribute 'xxx'",))
 >> CurrentSetattr
 vim.current.line = True:(<class 'TypeError'>, TypeError('bad argument type for built-in operation',))
-vim.current.buffer = True:(<class 'TypeError'>, TypeError('expected vim.Buffer object',))
-vim.current.window = True:(<class 'TypeError'>, TypeError('expected vim.Window object',))
-vim.current.tabpage = True:(<class 'TypeError'>, TypeError('expected vim.TabPage object',))
+vim.current.buffer = True:(<class 'TypeError'>, TypeError('expected vim.Buffer object, but got bool',))
+vim.current.window = True:(<class 'TypeError'>, TypeError('expected vim.Window object, but got bool',))
+vim.current.tabpage = True:(<class 'TypeError'>, TypeError('expected vim.TabPage object, but got bool',))
 vim.current.xxx = True:(<class 'AttributeError'>, AttributeError('xxx',))
 3,xx
 before
diff --git a/src/version.c b/src/version.c
index bf9b2b3..2004a94 100644
--- a/src/version.c
+++ b/src/version.c
@@ -729,6 +729,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1230,
+/**/
     1229,
 /**/
     1228,