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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 create(self):
 """ Subscribes at the server. """

        self.logger.debug('Create subscription on server...')

        if not self.connection.connected:
            self.state = 'connection_pending'
            return

        data = {
            'command': 'subscribe',
            'identifier': self._identifier_string()
        }

        self.connection.send(data)
        self.state = 'pending'