class _Missing(object):

    def __repr__(self):

        return 'no value'

    def __reduce__(self):

        value = obj.__dict__.get(self.__name__, _missing)

        if value is _missing:

            value = self._func(obj)

            obj.__dict__[self.__name__] = value

        return value

class ThreadLocalLazyProperty(LazyProperty):

    """

    Same as above but uses thread local dict for cache storage.

    """