Python and strategy pattern

[Gribouillis]

If you come from the Java world, don't think ABCMeta plays a similar role in Python as interfaces do in Java. I would have written these classes with a base class, but without using the abc module. You're adding an unnecessary complexity in the code. I think python's abc is only useful for extremely general functionalities, such as in collections.abc, otherwise it will come in your way rather than help you. Without ABCMeta, you can simply raise NotImplementedError in the base class' method. Last but not least, use python 3!