end it to, so it doesn't do
    anything. In order to get it do perform some kind of action, we
    need to give it a target object and a message to send. Then, when
    we click the button, it will send the message we specify to the
    target we provide. Naturally, the target object had better be able
    to respond to the message, or else we'll just see a runtime
    error.</p>

    <p>Let's define a class that knows how to respond to a greeting
    message, and then make an object of that class to serve