code: def cancel(self, queue):
          
          try:
              del self.consumers[queue]
          except KeyError:
              pass
          if self.client:
              return self.client.cancel(queue)
docs: Cancel the consumer for a queue.
  
          This removes the consumer from the list of consumers to be configured for
          every connection.
  
          Args:
              queue (str): The name of the queue the consumer is subscribed to.
          Returns:
              defer.Deferred or None: Either a Deferred that fires when the consumer
                  is canceled, or None if the consumer was already canceled. Wrap
                  the call in :func:`defer.maybeDeferred` to always receive a Deferred.