code: func (d *Dispatcher) OnConsensus(channel string, sender uint64, request *orderer.ConsensusRequest) error {
  	receiver := d.ChainSelector.ReceiverByChain(channel)
  	if receiver == nil {
  		d.Logger.Warningf("An attempt to send a consensus request to a non existing channel (%s) was made by %d", channel, sender)
  		return errors.Errorf("channel %s doesn't exist", channel)
  	}
  	return receiver.Consensus(request, sender)
  }
docs: // OnConsensus notifies the Dispatcher for a reception of a StepRequest from a given sender on a given channel