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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 read_welcome_message(self):
        '''Read the welcome message.

        Coroutine.
        '''
        reply = yield from self._control_stream.read_reply()

        self.raise_if_not_match(
            'Server ready', ReplyCodes.service_ready_for_new_user, reply)