diff --git a/android/util.go b/android/util.go
index 29bb9b1..854d782 100644
--- a/android/util.go
+++ b/android/util.go
@@ -54,7 +54,7 @@
 	return s
 }
 
-func indexList(s string, list []string) int {
+func IndexList(s string, list []string) int {
 	for i, l := range list {
 		if l == s {
 			return i
@@ -64,11 +64,11 @@
 	return -1
 }
 
-func inList(s string, list []string) bool {
-	return indexList(s, list) != -1
+func InList(s string, list []string) bool {
+	return IndexList(s, list) != -1
 }
 
-func prefixInList(s string, list []string) bool {
+func PrefixInList(s string, list []string) bool {
 	for _, prefix := range list {
 		if strings.HasPrefix(s, prefix) {
 			return true
@@ -77,6 +77,37 @@
 	return false
 }
 
+func FilterList(list []string, filter []string) (remainder []string, filtered []string) {
+	for _, l := range list {
+		if InList(l, filter) {
+			filtered = append(filtered, l)
+		} else {
+			remainder = append(remainder, l)
+		}
+	}
+
+	return
+}
+
+func RemoveListFromList(list []string, filter_out []string) (result []string) {
+	result = make([]string, 0, len(list))
+	for _, l := range list {
+		if !InList(l, filter_out) {
+			result = append(result, l)
+		}
+	}
+	return
+}
+
+func RemoveFromList(s string, list []string) (bool, []string) {
+	i := IndexList(s, list)
+	if i != -1 {
+		return true, append(list[:i], list[i+1:]...)
+	} else {
+		return false, list
+	}
+}
+
 // FirstUniqueStrings returns all unique elements of a slice of strings, keeping the first copy of
 // each.  It modifies the slice contents in place, and returns a subslice of the original slice.
 func FirstUniqueStrings(list []string) []string {