code: def _as_json_dumps(self, indent: str='   ', **kwargs) -> str:
          
          return json.dumps(self, default=self._default, indent=indent, **kwargs)
docs: Convert to a stringified json object.
  
          This is the same as _as_json with the exception that it isn't
          a property, meaning that we can actually pass arguments...
          :param indent: indent argument to dumps
          :param kwargs: other arguments for dumps
          :return: JSON formatted string