Advanced RegEx tutorial for Python

Regular Expressions (RegEx) are powerful programmer's tool. With one line of text we can accomplish what would require 100 lines of normal code. Unfortunately RegEx are very complicated. And it's not easy to become fluent with RegEx syntax. Maybe because the documentation is usually short and too detailed. Maybe because all RegEx tutorials in the net are for beginners. Anyway, here is my compressed tutorial about "advanced" Regular Expressions for Python programming language. Enjoy!