code: func (o *MockOracle) GetTimestamp(context.Context) (uint64, error) {
  	o.Lock()
  	defer o.Unlock()
  
  	if o.stop {
  		return 0, errors.Trace(errStopped)
  	}
  	physical := oracle.GetPhysical(time.Now().Add(o.offset))
  	ts := oracle.ComposeTS(physical, 0)
  	if oracle.ExtractPhysical(o.lastTS) == physical {
  		ts = o.lastTS + 1
  	}
  	o.lastTS = ts
  	return ts, nil
  }
docs: // GetTimestamp implements oracle.Oracle interface.