def METHOD_NAME(cid, classes):
    if len(classes) == 0:
        for name, obj in inspect.getmembers(sys.modules[__name__]):
            if inspect.isclass(obj):
                try:
                    classes[obj.cid] = obj
                except AttributeError:
                    pass
    if cid in classes:
        return classes[cid]
    else:
        return None