list iterators now support start, stop e step

iterator.go

@@ -9,6 +9,18 @@ import (
 	"fmt"
 )
 
+// Operator names
+
+const (
+	initName    = "init"
+	cleanName   = "clean"
+	resetName   = "reset"
+	nextName    = "next"
+	currentName = "current"
+	indexName   = "index"
+	countName   = "count"
+)
+
 type Iterator interface {
 	Next() (item any, err error) // must return io.EOF after the last item
 	Current() (item any, err error)