def on_save(self, uploaded_file):
        uploaded_file['changed'] = 'OLD'
        uploaded_file['hello'] = 'World'
        uploaded_file['deleted'] = False
        del uploaded_file['deleted']
        uploaded_file['changed'] = 'NEW'
        uploaded_file['deleted_attr'] = False
        del uploaded_file.deleted_attr

        try:
            del uploaded_file.missing_attr
        except __HOLE__:
            uploaded_file.missing_attr_trapped = True
dataset/ETHPy150Open amol-/depot/tests/test_fields_basic.py/DictLikeCheckFilter.on_save