Fix broken attr_add_code

wrappers/modelverse.py

@@ -841,7 +841,7 @@ def attr_assign_code(model_name, ID, attr, code):
 
     _goto_mode(MODE_MODIFY, model_name)
 
-    _input(["attr_add", ID, attr])
+    _input(["attr_add_code", ID, attr])
     _handle_output("Waiting for code constructors...")
     _input(compiled)
     _output("Success")