code: func (h Handler) ServeUnix(addr string, gid int) error {
  	l, spec, err := newUnixListener(addr, gid)
  	if err != nil {
  		return err
  	}
  	if spec != "" {
  		defer os.Remove(spec)
  	}
  	return h.Serve(l)
  }
docs: // ServeUnix makes the handler to listen for requests in a unix socket.
  // It also creates the socket file in the right directory for docker to read.