message: Fix Python warning in stub generation
diff: @@ -174,7 +174,7 @@ def process_class(_, obj, indent=0):
  process_function('__call__', obj.__call__, indent=indent + 4)
  for k, v in classes:
  - if k is not 'MaskType':
  + if k != 'MaskType':
  process_class(k, v, indent=indent + 4)
  if len(properties) > 0:
  