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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 publish(self, **kwargs):
 r""" Publishes state information. :Keyword Arguments: * *topic* (``string``) -- [REQUIRED] The name of the MQTT topic. * *payload* (``bytes or seekable file-like object``) -- The state information, in JSON format. :returns: None """


        topic = self._get_required_parameter('topic', **kwargs)

        # payload is an optional parameter
        payload = kwargs.get('payload', b'')

        function_arn = ROUTER_FUNCTION_ARN
        client_context = {
            'custom': {
                'source': MY_FUNCTION_ARN,
                'subject': topic
            }
        }

        customer_logger.info('Publishing message on topic "{}" with Payload "{}"'.format(topic, payload))
        self.lambda_client._invoke_internal(
            function_arn,
            payload,
            base64.b64encode(json.dumps(client_context).encode())
        )