# File lib/pry-remote-em/client.rb, line 218
    def authenticate
      return fail("[pry-remote-em] authentication required") unless @auth
      return fail("[pry-remote-em] can't authenticate before negotiation complete") unless @negotiated
      user, pass = @auth.call
      return fail("[pry-remote-em] expected #{@auth} to return a user and password") unless user && pass
      send_auth([user, pass])
    end