code: def open(self):
          
          return self._framework.chain_return_value(self._ensure_file(),
                                                    self.get_io_loop(),
                                                    self)
docs: Retrieve this file's attributes from the server.
  
          Returns a Future.
  
          .. versionchanged:: 2.0
             No longer accepts a callback argument.
  
          .. versionchanged:: 0.2
             :class:`~motor.MotorGridOut` now opens itself on demand, calling
             ``open`` explicitly is rarely needed.