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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 close(self):
 """ Sends a shutdown signal to the unity environment, and closes the socket connection. """

        if self._socket is not None and self._conn is not None:
            message_input = UnityMessage()
            message_input.header.status = 400
            self._communicator_send(message_input.SerializeToString())
        if self._socket is not None:
            self._socket.close()
            self._socket = None
        if self._socket is not None:
            self._conn.close()
            self._conn = None