code: function AuthExample() {
    return (
      <Router>
        <div>
          <AuthButton />
          <ul>
            <li>
              <Link to="/public">Public Page</Link>
            </li>
            <li>
              <Link to="/protected">Protected Page</Link>
            </li>
          </ul>
          <Route path="/public" component={Public} />
          <Route path="/login" component={Login} />
          <PrivateRoute path="/protected" component={Protected} />
        </div>
      </Router>
    );
  }
docs: ////////////////////////////////////////////////////////// 1. Click the public page 2. Click the protected page 3. Log in 4. Click the back button, note the URL each time