state = {
    login: false
  };

  componentWillMount() {
    this.authListener();
  }

  authListener = () => {
    auth.onAuthStateChanged(user => {
      if (user) {
        this.setState({
          login: true
        });
      } else this.setState({ login: false });
    });
  };

  redirectOnLogIn = () => {
    let { login } = this.state;
    if (!login) {
      return <Auth />;
    } else {
      return <Users />;
    }
   };