Iterator: added support for iterators over dictionaries

iterator.go

@@ -21,6 +21,8 @@ const (
 	CountName   = "count"
 	FilterName  = "filter"
 	MapName     = "map"
+	KeyName     = "key"
+	ValueName   = "value"
 )
 
 type Iterator interface {
@@ -29,14 +31,14 @@ type Iterator interface {
 	Current() (item any, err error)
 	Index() int
 	Count() int
+	HasOperation(name string) bool
+	CallOperation(name string, args map[string]any) (value any, err error)
 }
 
 type ExtIterator interface {
 	Iterator
 	Reset() error
 	Clean() error
-	HasOperation(name string) bool
-	CallOperation(name string, args map[string]any) (value any, err error)
 }
 
 func errNoOperation(name string) error {