 as our
    button's target.</p>

    <p>We can define a subclass of <code>NSObject</code> to handle
    our button's message:</p>

    <pre>
(defclass greeter (ns:ns-object)
  ()
  (:metaclass ns:+ns-object))
#&lt;OBJC:OBJC-CLASS GREETER (#x13BAF810)&gt;
    </pre>

    <p>We'll need to define a method to execute in response to the
    button's message. Action methods accept one argument (in addition
    to the receiver): a sender. Normally Cocoa passes the button
    object itself as the sender argument; 