As mentioned previously, graphic user interface (GUI) programming relies heavily on object-oriented principles. In the case of our program, we need to define a class that will then be called by the main function.
We are using the Tkinter toolkit and not recreating it, so we will create an inherited class that relies on Tkinter's Frame class.
From there, we will next define functions for each window or frame that we want our program to create.
class Greeter (Frame):