code: func NewEpoller() (*Epoller, error) {
  	efd, err := unix.EpollCreate1(unix.EPOLL_CLOEXEC)
  	if err != nil {
  		return nil, err
  	}
  	return &Epoller{
  		efd:       efd,
  		fdMapping: make(map[int]*EpollConsole),
  	}, nil
  }
docs: // NewEpoller returns an instance of epoller with a valid epoll fd.