Since we need a single button to toggle between pause and unpause, we will again use the cycle() method from the itertools module. Define an attribute, as follows (see code 5.04—view.py):

toggle_pause_unpause = itertools.cycle(["pause","unpause"])

Then, modify the command callback attached to the button, as follows:

def on_pause_unpause_button_clicked(self):
 action = next(self.toggle_pause_unpause)
 if action == 'pause':
   self.player.pause()
 elif action == 'unpause':
   self.player.unpause()

This takes care of the pause and unpause features of the program.