* fix:
1. infernce multi card occupy
2. facebox model inference occupy too much
test=develop

* refine python api comments: shuffle, while, scale, sampled_softmax_with_cross_entropy, scatter,
round, sin, sqrt, shape, split, soft_relu, slice, selu, ifelse, switch.
test=develodp

* fix conflict error.
test=develop

* fix doc in transpiler, test=develop

* add gradient clip in minimize; test=develop

* fix bug; test=develop

* fix format; test=develop

* move new grad clip to dygraph/grad_clip.py; test=develop

* fix lr decay and grad clip test; test=develop

* seperate dygraph grad clip; test=develop

* fix grad clip test; develop

* fix api spec bug; test=develop

* add blank line, test=develop,test=document_preview

to fix format problem

* update python APIs

test=document_preview test=develop

* update API.spec

test=document_preview

test=develop

* update merge_selected_rows

* update API.spec

test=document_preview

test=develop

* update API.spec

test=document_preview

test=develop

* fix the comment of less_than

test=develop

test=document_preview

* update API.spec

test=develop

test=document_preview

* update API.spec

test=develop

test=document_preview

* update API.spec

test=develop

test=document_preview

* update API.spec

test=develop

* update API

test=develop

* [DOC] Fix api docs, test=develop, test=document_preview

* [DOC] Fix api annotation: fluid.layers.tensor_array_to_tensor. test=develop, test=document_preview

* test=develop, test=document_preview

update MD5 of tensor_array_to_tensor

* fix the api example for create_global_var, create_parameter, SGDOptimizer, RMSPropOptimizer, MomentumOptimizer, LarsMomentumOptimizer, FtrlOptimizer
test=develop

* add example for adamoptimizer
fix API.spec
test=develop

* test=develop

* test=develop

* Bias correction for exponential moving average

test=develop, test=document_preview

* Fix docs

test=develop, test=document_preview

test=develop

* fix the bug that sub_scope_ may be null in AnalysisPredictor::Run.

* add more directions about io APIs' docs.

* update the API.spec. test=develop test=document_preview

* add data parallel batch

* fix example; test=develop

* fix api spec; test=develop

* fix api spec; test=develop

* add doc check
test=develop
test=document_preview

* test=develop,test=document_preview

add blank line to fix format, add one more "import"

* fix bug; test=develop

* fix bug; test=develop

* Fix the example code in some Python API.
test=develop

* Fix the example code in some Python API by adding import.
test=develop

Python examples of fluid.layers.io.double_buffer and some BuildStrategy's methods.

* test=develop

* test=develop

* test=develop

* del #

* Add exponential moving average

test=develop, test=document_preview

* Polish documents

test=develop, test=document_preview

* Update API spec

test=develop, test=document_preview

* fix api example. test=develop

* fix API.spec. test=develop

* fix spectral_norm format. test=develpp

* merge develop

* add import. test=develop

* fix indent. test=develop

* fix indent. test=develop

* add import fluid. test=develop

* fix distribute doc

* fix bpr data_norm teacher_student_sigmoid , test=develop test=document_preview

修复了bpr_loss data_norm teacher_student_sigmoid_loss三个api, 同时修复了continuous_value_model文档英文拼写错误

* fix api doc according to the reviewer's comment test=develop

* Fix examples of fluid.layers.sums.
test=document_preview

* Correct the example of DynamicRNN and its functions.
test=develop

* Add 'import paddle.fluid as fluid' to examples.
test=develop

* Update API.spec.
test=develop

* Add space lines.
test=develop

* Update the API.spec.
test=develop

* Add LAMB optimizer

* Expose LAMB Optimizer's APIs

test=develop, test=document_preview

* Cleanup code & doc

test=develop, test=document_preview

* Update lamb optimizer's formula

test=develop

* Add api doc code examples

add or fix topk, squeeze, stack, StaticRNN,
StaticRNN memory in doc

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* Add squeeze md5.

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* Add import package

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* improve the doc of paddle.fluid.memory_optimize, test=develop

* fix typo, test=develop

* fix data_feed_desc.py example run error
test=develop
test=test=document_preview

* fix data_feed_desc.py example display error
test=develop
test=document_preview

* update API.spec for DataFeedDesc
test=develop
test=document_preview

* improve the API Sample of DataFeeder, memory_optimize and release_memory, test=develop

* update API.spec, test=develop, test=document_preview

* tweak the code format of feed API, test=develop

*  update API.spec, test=develop

* improve doc for DataFeeder and default_main_program, test=develop

* init auto loss scaling

test=develop

* change API.spec

* change ifelse to switch and use reduce_sum to optimize checking isfinite

test=develop

* Remove redundant code

test=develop

* test=develop

* test=develop

* test=develop

* add collect fpn proposals op,test=develop

Fix some api example codes' bugs and these APIs include load_inference_model, load_vars, save_vars, L1DecayRegularizer and L2DecayRegularizer. (#17324)

* fix some api example codes' bugs.

* update API.spec. test=develop test=document_preview

* add import fluid. test=develop test=document_preview

* test=develop
add sign op

* Update nn.py

test=develop
delete stop_gradient assignment

* Fix the example code in some Python API
* Update paddle/fluid/API.spec
* Fix some examples format

* test=develop, test=document_preview, fix all 13 api doc and code

* test=develop, fix rst

* test=develop, refresh API.spec

* reset drop local scope counter
test=develop

* test=develop
add elementwise_mod and elementwise_floordiv, fix equation problem in elementwise_mod