class UpperAttrMetaclass(type):

    def __new__(upperattr_metaclass, future_class_name,
        future_class_parents, future_class_attr):
        attrs = ((name, value) for name, value in list(future_class_attr.items()) if
            not name.startswith('__'))
uppercase_attr = dict((name.upper(), value) for name, value in attrs)
How do Django models work?