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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 stop(self):
 """Disconnect from device."""

        if self._outstanding:
            _LOGGER.warning('There were %d outstanding requests',
                            len(self._outstanding))

        self._initial_message_sent = False
        self._outstanding = {}
        self._one_shots = {}
        self.connection.close()