Python Graphical User Interface (GUI) Using PyQt5: Basic - Part 1

I am not a big fan of GUI. I do not like developing the front-end of the program. For me, personally, developing the back-end of the program is more fun. However, if you are the only developer in a company, or in my case the only data scientist in my company, then developing a GUI is a must. Why? Because nobody gives a sh*t about the back-end. What they want is something that they can interact with, something that is "beautiful", and the final result.

General overview of the whole structure of the program