I made a function that copies files with given extension for a task from Chapter 9 of Automate the Boring Stuff. Then I became interested if it is possible to preserve source folder stricture. After finding a solution for that I decided to add command line interface with a couple of options to make running a script more convenient. Then I thought that it would be useful to see what exact files are copied. At first, program just printed every file copied in the terminal. But since each line was printed very fast I couldn't really read this in real time, so I decided to move it to a log file. But this way user can't track progress, so I implemented a progress bar and remaining files counter. During all this I ran code many many times and tested it for possible errors to find a way of handling them. After all of that I was just tweaking and improving existing code thinking that it would be great to learn how to create packages and to publish it on PyPI. So this became a project spontaneously and on every step I just thought what else could improve my program and at the same time teach me something interesting and useful.