code: func (eew exitErrorWrapper) ExitStatus() int {
  	ws, ok := eew.Sys().(syscall.WaitStatus)
  	if !ok {
  		panic("can't call ExitStatus() on a non-WaitStatus exitErrorWrapper")
  	}
  	return ws.ExitStatus()
  }
docs: // ExitStatus is part of the ExitError interface.