def __init__(self):
        super(PrefetchManagerMixin, self).__init__()
        for name, prefetcher in self.prefetch_definitions.items():
            if prefetcher.__class__ is not Prefetcher and not callable(prefetcher):
                raise InvalidPrefetch(name % "Invalid prefetch definition %s. This prefetcher needs to be a class not an instance.")
dataset/ETHPy150Open ionelmc/django-prefetch/src/prefetch.py/PrefetchManagerMixin.__init__/swapped operands of `%`