code: func (o *MockOrderer) SendBroadcast(ctx reqContext.Context, envelope *fab.SignedEnvelope) (*common.Status, error) {
  	// Report this call to the listener
  	if o.BroadcastListener != nil {
  		o.BroadcastQueue <- envelope
  	}
  	select {
  	case err := <-o.BroadcastErrors:
  		return nil, err
  	default:
  		return nil, nil
  	}
  }
docs: // SendBroadcast accepts client broadcast calls and reports them to the listener channel
  // Returns the first enqueued error, or nil if there are no enqueued errors