Events in our text editor

First things first: we should ensure that we have some expected key-bindings happening within our Text widget. We'll collate these in a method called bind_events and call this method from within our __init__:

def __init__(self):
    ...    
    self.bind_events()

def bind_events(self):
    self.bind('<Control-a>', self.select_all)
    self.bind('<Control-c>', self.copy)
    self.bind('<Control-v>', self.paste)
    self.bind('<Control-x>', self.cut)
    self.bind('<Control-y>', self.redo)
    self.bind('<Control-z>', self.undo)

This function now ensures that six commonly used keyboard shortcuts will perform their expected behaviors.

Since these behaviors are already handled by the Text widget (except for select_all), we only need to emit the relevant events in order...