How to use Messagebox.askyesno in Python code example

Example: how to handle response from tkinter messagebox.askquestion() function in Python

def new_game_confirm(self):
        result = messagebox.askquestion("Start a new game", "Are you sure you want to start a new game ? Your current campaign will be overriden and there is no going back !", icon='warning')
        if result == 'yes':
            self.proceed_to_new_game_menu()
        else:
            pass