@classmethod
def registered(cls, e_type):
    """
        Returns True if the given entity type is registered, False otherwise.
        """
    result = None
    try:
        result = e_type.name in [e_type.name for e_type in cls.types]
    except AttributeError:
        result = e_type in [e_type.name for e_type in cls.types]
    return result
