What are metaclasses? What are they used for?
I saw an interesting use case for metaclasses in a package called classutilities. It checks if all class variables are in upper case format (it is convenient to have unified logic for configuration classes), and checks if there are no instance level methods in class.
Another interesting example for metaclases was deactivation of unittests based on complex conditions (checking values of multiple environmental variables).
What are metaclasses in Python?