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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def open(self):
 """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. """

        return self._framework.chain_return_value(self._ensure_file(),
                                                  self.get_io_loop(),
                                                  self)