* The first version of plato2. Not finished the network.

* Update decode stratage.

* Update decode stratage.

* Completed the encoder and decoder. But it will oom.

* Completed the encoder and decoder.

* backend the code.

* Only completed the network of plato2 and nsp.

* Completed the development. But the effect has not be verified.

* Add readme and remove the code about deal PY2 and PY3.

* Modify comment.

* Modify readme and add images.

* Delete the data folder.

update docs for ernie-tiny

add ernie_gen for the dygraph mode

* fix translation dataset and simplify transformer reader

update codes for paddenlp text cls example

* update seq2seq, using paddlenlp

* Using new paddlenlp API

* update seq2seqREADME

* wrap dev ds

* delete useless comments

* update predict.py

* using paddlenlp.bleu

* remove shard

* update README, using bleu perl

* delete cand

* Remove tokens that make sentences longer than max_len

* remove pdb

* remove useless code.

* update url and dataset name of vae dataset(ptb and yahoo)

* update seq2seq and vae, data and README

update the readme for the word_embedding (#5050)

* add all wiki embedding and part of baidu encyclopedia embedding.

* add embedding example

* add people_daily, weibo, sougou pretrained embedding

* add zhihu, finacial,literature embedding

* Add embedding model readme; add embedding train example and readme

* fix README example

* fix embedding doc

* add paddle.models api reference docs

* update docs

* update docs

* update docs

* tmp

* update docs

* update docs

* update docs

* update docs

* update docs

* update docs

* fix translation.py bugs

* delete useless comments

* set couplet download root None

* add paddle.models api reference docs

* update docs

* update docs

* update docs

* tmp

* update docs

* update docs

* update docs

* update docs

* update transformer doc

* Update transformers.md

* Update transformers.md

* update transformer doc

* Update transformers.md

* update couplet readme

* update generation example

* add metric readme doc

* add "`" for APIs in doc

* Update README.md

Add "`" for APIs in doc

* Update metrics.md

* Update README.md

* update metric readme

* update lrscheduler

* minor fix

* add pre-commit

* minor fix

* Add __len__ to squad dataset

* minor fix

* Add dureader robust prototype

* dataset implement

* minor fix

* fix var name

* add dureader-yesno train script and dataset

* add readme and fix md5sum

* integrete dureader datasets

* change var names: segment to mode, root to data_file

* minor fix

* update var name

* Fix api bugs

* add dataset readme

* add express ner

* update readme format

* fix format bug

* change readme path

* fix format bug

* fix dataset bug

* add couplet

* simplify model code

* simplify code

* update couplet README

* add pad_token to TranslationDataset, update CoupletDataset

* update couplet url, add couplet generation example

* update TranslationDataset

* upadte classname to self in __init__

* update README.md

* update lrscheduler

* minor fix

* add pre-commit

* minor fix

* Add __len__ to squad dataset

* minor fix

* Add dureader robust prototype

* dataset implement

* minor fix

* fix var name

* add dureader-yesno train script and dataset

* add readme and fix md5sum

* integrete dureader datasets

* change var names: segment to mode, root to data_file

* minor fix

* update var name

* Fix api bugs

* add dataset readme

* add express ner

* update readme format

* fix format bug

* change readme path

* fix format bug

* update lrscheduler

* minor fix

* add pre-commit

* minor fix

* Add __len__ to squad dataset

* minor fix

* Add dureader robust prototype

* dataset implement

* minor fix

* fix var name

* add dureader-yesno train script and dataset

* add readme and fix md5sum

* integrete dureader datasets

* change var names: segment to mode, root to data_file

* minor fix

* update var name

* Fix api bugs

* add dataset readme

* add express ner

* update readme format

* add paddle.models api reference docs

* update docs

* update docs

* update docs

* 1. move PAD to the end
2. Add Readme.md

* optimize readme doc

Co-authored-by: Nwawltor <fanzeyang0904@hotmail.com>

* add paddle.models api reference docs

* update docs

* update docs

* update transformer doc

* Update transformers.md

* Update transformers.md

* update SamplerHelper.batch

* update batch_size, delete a useless log

* update SamplerHelper.batch

* update SamplerHelper.batch, change cmp_fn arg to key

* Update TranslationDataset and IWSLT

* fix doc error

* update rouge-l, move default_trans_func to utils

* fix error info bugs

* add score method for metric bleu and rouge-l

* update bleu doc

* Add Express Example

* Add Express Data

* Add Ernie for Express Example

* add the express for the paddlenlp

* remove the ernie_crf file
Co-authored-by: Nwanghuijuan03 <wanghuijuan03@baidu.com>