3 Answers
+ 7
You can do challenges to see how much you learn and to practice. Also you can search in Q&A section challenges to see some "challenges" post by community members.
+ 3
codingbat, codewars and hackerrank are all good sites for coding exercises. Your code is run against tests, and it will have to pass all the tests. Each of these sites supports Python as well as other languages.
+ 2
CodePlayground (here)? Then you get community attention, and you can compare other learner's codes, do Q&A challenges, etc. There are lists of "make a program that does..." out there for ideas (like 'list of Python challenges')