code: func UsersHandlerOption(users ...*url.Userinfo) HandlerOption {
  	return func(opts *HandlerOptions) {
  		opts.Users = users
  
  		kvs := make(map[string]string)
  		for _, u := range users {
  			if u != nil {
  				kvs[u.Username()], _ = u.Password()
  			}
  		}
  		if len(kvs) > 0 {
  			opts.Authenticator = NewLocalAuthenticator(kvs)
  		}
  	}
  }
docs: // UsersHandlerOption sets the Users option of HandlerOptions.