+ out = json.dumps([{'id': f['id'], 'height.:2': str(f['height'])[:2]}
+ if 'height' in f else {'id': f['id']}
+ for f in FORMATS])
+ test('%(formats.:.{id,height.:2})j', (out, sanitize(out)))
+ test('%(formats.:.{id,height}.id)l', ', '.join(f['id'] for f in FORMATS))
+ test('%(.{id,title})j', ('{"id": "1234"}', '{"id": "1234"}'))