* [CodeStyle] remove all future import

* revert test_error.py

* restore future import in example code

* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* add add yaml

* add elementwise add yaml; test=develop

* add norm

* update

* add some yaml config; test=develop

* fix bug; test=develop

* fix compare error; test=develop

* revert erger_gen.py

* update; test=deveop

* remove usless code; test=deveop

* fix bug; test=develop

* fix test error; test=develop

* remove int_type; test=develop

* fix type error; test=develop

* format; test=develop

* remove type register; test=develop

* polish code; test=develop

* fix ci error; test=develop

* upgrade gather_tree to core.ops

* update gather_tree unittests

* fix error info for rnn related api

* passed local test, test=develop

* double check the code

* double check the code, test=develop

* update 'shape' check in RNNCell, test=develop

* add long dtype to RNNCell

* fix long type in python3
Co-authored-by: NXingWu01 <wuxing@iie.ac.cn>

There are PythonAPI tests in Op's unittest which don't need to inherit OpTest class.