'Find versionable subclasses which subclass.master_class == cls'

@classmethod
def _find_versionable_subclass(cls):

    subclasses = [cls]
    for sub in cls.__subclasses__():
        if (VersionableClass in list(sub.__bases__)):
            subclasses.extend(sub._find_versionable_subclass())
    return subclasses
