def _group_release_groups(self, metadata, only_ids=False):
        results = {}
        for item in metadata:
            id = item['release_group_id']
            if results not in id:
                results[id] = (self.extract_release_group(item, only_id=only_ids), [])
            results[id][1].append(item)
        return results.itervalues()
dataset/ETHPy150Open lalinsky/acoustid-server/acoustid/api/v2/__init__.py/LookupHandler._group_release_groups/swapped operands of `not in`