* move fc from fluid to paddle2.0

* fix unit test

* fix some examples

* fix some examples

* isort all files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* [CodeStyle][py2][U004] unecessary explicit `object` inheritance in class definition

* fix an increment

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* [CodeStyle] use built-in `open` instead of `io.open`

* revert flake8 config changes

* [CodeStyle] remove all future import

* revert test_error.py

* restore future import in example code

* update cpplint hook script

* update pre-commit config

* try trigger cpplint on ci

* Revert "try trigger cpplint on ci"

This reverts commit 895853453c5f68b587914713e313c92abb69fc45.

* empty commit, test=document_fix

* [CodeStyle] trim trailing whitespace in yaml and hook

* python incremental whitespace and yml files

* trim trailing whitespace

* fix `.cmake-format.py`

* revert npu ut changes, avoid npu ci error

test=document_fix;pre install clang-format to avoid repeat installation due to pre-commit multi-thread running (#43734)

* Fix cmakelint errors for generic.cmake

* Fix cmake errors

* test=document_fix

* cpplint set version 1.6.0;test=document_fix

* 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

* upgrade comment string to raw string

* fix string in

* fix string with ' '

* revert update on comments

* upgrade only necessary

* fix sample code checker

* fix comments with '''

This is part of big move of v2 codes to legacy sub dir.

* add lod_tensor util and modify pybind

* refind pybind LoDTensor API and modify LoDTensor and DataFeeder test

* fix test error

* fix detection map op test

* fix reorder_lod_tensor test

* fix seq_concat_op

* fix chunk evel op test

* fix target assign op

* fix warp ctc op

* address comments step 1: reverse reset_lod op

* step 2: modify op test

* add warning message

* remove has_valid_lod

* add back has_valid_lod

* address comments

* add exception catching trial

* enable docstring checker and fix comments

* update

* update by comments

* fix build