* delete old dygraph op test

* isort all files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* [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

* [Eager]Enhance eager_trace_op logic to support Optimizer Op

* fix AsDispensable

* [Eager]Fix 17 unittest and open check_eager=True

* remove print

* fix unittests

* fix op_testa

* fix coverage CI failed

* fix ci