* rewrite the sigmoid_focal_loss code example. test=develop

* fix spelling mistake in comments of code example.test=develop

* change print([.*].numpy()) to print([.*]) in example codes of sigmoid_focal_loss. test=document_fix

* Support pop for dict in dy2stat

* Move convert_pop to convert_operators.py and polish convert_pop

* fix tensor detach to zero copy

* fix tensor detach to zero copy

* add reminder of fluid.layers.lstm

* save one name in cross_entropy and softmax_cross_entropy, test=develop

* change used function in CrossEntropy from softmax_cross_entropy to cross_entropy, test=develop

Simple code clean up

test=document_fix

* Impelement 2.0 API version Conv2d and Linear layer quantization in imperative mode.

* use cudnn softmax in static Lenet

* Modified ChannelwiseQAT Unittest for 2.0 API.

* For CI python coverage.

remove eigen threadpool for the speed up

* Add multi_gru_fuse_pass and tests

* fix date

* cleaned up headers

* polish parallel api impl & doc details

* add unittest for coverage

* remove spawn test in py2.7

* add parallel api into white list

As the title

* add soft_label and axis for CrossEntropyLoss and improve performance,test=develop

* fix conflict in nn/functional/loss.py, test=develop

* fix some docs test=develop;test=document_fix

* add code example test=develop;test=document_fix

* fix code example test=develop;test=document_fix

* fix code example test=develop;test=document_fix

* fix code example test=develop;test=document_fix

* open unittests on windows

* open GPU unittest on windows

* fix clip by norm eng doc. test=develop

Add support for using tuple as tensor.shape (For example: a, b, c, d = x.shape)

* add lamb optimizer and unittest

* fix lamb

* fix lamb v2 op

* fix sampling id

* fix lamb sample code

* Update lamb.py

* fix doc

* fix doc

* Update lamb.py

* 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 '''

[Dynamic-to-Static] Fix bug of convert_logical_and/convert_logical_or: the operands are executed sequentially(#28993)

  
  1) The operands are executed sequentially according to the running logic of Python.
  
  2) If the left hand operand is True(for convert_logical_or)/False(for convert_logical_and), the right hand operand should be executed.

The PR description is long. See details in the PR link.

* fix eng doc, test=develop

* add import deprecated for layers, test=develop

* add block line for doc generate, test=develop

* remove todo for create_variable, test=develop

* add blank line for doc generate, test=develop

* add blank line for doc generate, test=develop

* Add multi_gru_seq_fuse_pass and tests

* fix date

* removed unused functions

* Fix en doc for rnn.py. test=document_fix

* Delete mq2007 dataset.

* polish dataloader doc detail, test=decument_fix

* fix commnet error

* fix word error

* test=develop, optimize global_step

* refine doc of bernoulli

* fix some problems

* fix unsqueeze

* fix squeeze

* fix doc

* update, test=develop

* fix English doc for dice_loss, log_loss, unfold and NLLLoss API test=document_fix

* add early stopping

* add doc for early stopping

* fix sample code bugs

* update infer of mode, update doc, add unittests to increase coverage rate

* fix sample code for early stopping

* update sample code and unittests

* reduce time cost of test_callbacks unittest

* fix model.py code style error