patch 9.0.1159: extends argument for class not implemented yet
Problem: Extends argument for class not implemented yet.
Solution: Basic implementation of "extends".
diff --git a/src/structs.h b/src/structs.h
index 78108c1..08edcf4 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1494,6 +1494,8 @@
int class_refcount;
int class_copyID; // used by garbage collection
+ class_T *class_extends; // parent class or NULL
+
// interfaces declared for the class
int class_interface_count;
char_u **class_interfaces; // allocated array of names