code: def _normalize_utf8_keys(kwargs):
    
    if any(type(key) is binary_type for key in kwargs.keys()):
      # This is to preserve the original dict type for kwargs.
      dict_type = type(kwargs)
      return dict_type([(text_type(k), v) for k, v in kwargs.items()])
    return kwargs
docs: When kwargs are passed literally in a source file, their keys are ascii: normalize.