title: PyQt Connect to KeyPressEvent
body: <p>Certain widgets will allow me to do:</p>
  
  <pre><code>self.widget.clicked.connect(on_click)
  </code></pre>
  
  <p>but doing:</p>
  
  <pre><code>self.widget.keyPressEvent.connect(on_key)
  </code></pre>
  
  <p>will fail saying that the object has no attribute 'connect'.</p>
  
  <p>I know that sub-classing the widget and re-implementing the <code>keyPressEvent</code> method will allow me to respond to the event. But how can I <code>.connect()</code> to the keyboard event thereafter, or otherwise said, from a user context?</p>