We create the Tkinter window as we did before; however, instead of defining all the items separately, we create a special class for the application buttons.
The class we create acts as a blueprint or specification of what we want the appButtons items to include. Each item will consist of a string value for app_cmd, a function called startApp(), and an __init__() function. The __init__() function is a special function (called a constructor) that is called when we create an appButtons item; it will allow us to create any setup that is required.
In this case, the __init__() function allows us to create a new Tkinter button with the text to be set to an item in app_list and the command to be called in the startApp() function when ...
