code: def qos(self, prefetch_count=0, prefetch_size=0, global_=False):
          
          if not compatibility.is_integer(prefetch_count):
              raise AMQPInvalidArgument('prefetch_count should be an integer')
          elif not compatibility.is_integer(prefetch_size):
              raise AMQPInvalidArgument('prefetch_size should be an integer')
          elif not isinstance(global_, bool):
              raise AMQPInvalidArgument('global_ should be a boolean')
          qos_frame = specification.Basic.Qos(prefetch_count=prefetch_count,
                                              prefetch_size=prefetch_size,
                                              global_=global_)
          return self._channel.rpc_request(qos_frame)
docs: Specify quality of service.
  
          :param int prefetch_count: Prefetch window in messages
          :param int/long prefetch_size: Prefetch window in octets
          :param bool global_: Apply to entire connection
  
          :raises AMQPInvalidArgument: Invalid Parameters
          :raises AMQPChannelError: Raises if the channel encountered an error.
          :raises AMQPConnectionError: Raises if the connection
                                       encountered an error.
  
          :rtype: dict