modern for loop
typo in variable name + add a getter for it
It's probably a good idea to not switch to the lesson until it's completely initialized
more informative error message
Basic testing infrastructure

This simply only that python entities manage to solve the Java worlds.

It could be extended in many way, including:
 - this shoud be converted to junit
 - this should share more code with usual mutation process to catch more issues

But at least, we have a testing infrastructure!
fix lessons/welcome/basics/BasicsEntity.py so that it passes our newly created test suite