code: func (m *MockEventService) RegisterTxStatusEvent(txID string) (fab.Registration, <-chan *fab.TxStatusEvent, error) {
  	eventCh := make(chan *fab.TxStatusEvent)
  	reg := &dispatcher.TxStatusReg{
  		Eventch: eventCh,
  		TxID:    txID,
  	}
  	m.TxStatusRegCh <- reg
  
  	if !m.Timeout {
  
  		go func() {
  			select {
  			case txStatusReg := <-m.TxStatusRegCh:
  				txStatusReg.Eventch <- &fab.TxStatusEvent{TxID: txStatusReg.TxID, TxValidationCode: m.TxValidationCode}
  			case <-time.After(5 * time.Second):
  				panic("time out not expected")
  			}
  		}()
  
  	}
  
  	return reg, eventCh, nil
  }
docs: // RegisterTxStatusEvent registers for transaction status events.