docs: def appendQKeyEvent(self, keyEvent: QtGui.QKeyEvent):
          """
          Append another key to the key sequence represented by this object.
  
          |Args|
  
          * ``keyEvent`` (**QKeyEvent**): the key to add.
  
          |Returns|
  
          **None**
  
          |Raises|
  
          * **QtmacsArgumentError** if at least one argument has an invalid type.
          """
          # Store the QKeyEvent.
          self.keylistKeyEvent.append(keyEvent)
  
          # Convenience shortcuts.
          mod = keyEvent.modifiers()
          key = keyEvent.key()
  
          # Add the modifier and key to the list. The modifier is a
          # QFlag structure and must by typecast to an integer to avoid
          # difficulties with the hashing in the ``match`` routine of
          # the ``QtmacsKeymap`` object.
          self.keylistQtConstants.append((int(mod), key))