In an effort to better understand Python while in school, I came across a book called Head First Python by Paul Barry. It is organized
differently than most coding books, relying on humour and an approach better adapted to how the brain actually learns. Sure, you start with the "Hello World" beginner programming but you keep building on it
and learning Python along the way. This edition starts with a word search app that returns asked for letters or numbers from a phrase, word, number string.
By about halfway through the book you've got an app ready for web deployment
using Flask. The folks at pythonanywhere will let you host your python apps
(first one is free).
Try it out below. Not only can it return the default vowels, it will return any characters you ask for.