render() for part 2 of blockstack tutorial

App.js

  render() {
    const { userSession, currentUser } = this.state;
    return (
      <div className="App">
        {userSession.isUserSignedIn() ? (
          <div className="hello">
            <h2>Hello {currentUser.username} !</h2>
            <button className="button" onClick={this.handleSignOut}>
              <strong>Sign Out</strong>
            </button>
          </div>
        ) : (
          <button className="button" onClick={this.handleSignIn}>
            <strong>Sign In</strong>
          </button>
        )}
      </div>
    );
  }