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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:
 async def unsubscribe(self, topic: str):
 """Unsubscribe from a topic :param topic: required :returns: None Sample ws response .. code-block:: python { "id": "1545910840805", "type": "ack" } """


        req_msg = {
            'type': 'unsubscribe',
            'topic': topic,
            'response': True
        }

        await self._conn.send_message(req_msg)