* 增加方法获取和执行全量api的示例代码进行测试

* start the sample code test for gpu

* should import paddle separately

* add a stdout handler, the default is stderr. the paddle_build.sh will catch the stdout content.

* add RUN_ON_DEVICE into the requires set

* if codeblok['required'] is empty, use the RUN_ON_DEVICE instead

* set the threads to 16

http://agroup.baidu.com/paddlepaddle-org-cn/md/article/4036225

* 设置默认日志级别为INFO级别

* using the logic from gen_doc.py

* using modulelist to get the all apis

* as we don't care which name is the shorttest, so fetch the first name in the all_names list

* the new list from project

* 先不启用gpu测试，先把print_signature获取不到全部API的问题解决了

* UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 1788: ordinal not in range(128)

test=document_fix

str(doc) in python2

test=document_fix

* update md5 function in count_api_without_core_ops.py

str in py2 is different.

test=document_fix

* update testcases

* remove unused codes

* update the docstring for samcd_processor

* no need to import the six module

* 我也不知道为何有一个前导空格，但现在有单元测试，取消这个空格没啥问题

* add unittests for print_signatures; add the first case for 'required' mechanism when executing sample code testing

* there is no paddle installed in PR-CI-APPROVAL

test=document_fix

* print the real name for Functions instead of the ArgSpec

class function method

* some API's name is not __module__ + __name__

so, we disard them temporarily.

* update the logging format for console

* ommit the top level of paddle package.

* these APIs have been removed.

test=document_fix

* Another Error occerd

* print_signatures.py 's stdout is redirect to spec file, so should not print any other info.

so sad.

* print the error msg to stderr

* disable the __init__ magic method

* update unittest for sampcd_processor.py

update unittest for sampcd_processor.py

* PR-CI-APPROVAL 's python interpreter name is not 'python3'.

it's a python3.9;
it does not have paddle installed yet.

此句在CI流水线竟然不可以用。报python3找不到
此句在CI流水线竟然不可以用。因为环境没有安装paddle

* testing only extract api from __all__

paddle module(the top module) does not have __add__
test=document_fix

* should import paddle here

* update the mechanism of extractiong and executing for the sample-codes test.

更新抽取代码和执行代码的逻辑
优化输出打印

* good code style

* use alias name instead of original name for alias API

* refine log message

* split api_spec document;test=document_fix

* change tools

* test=develop;test=document_fix

* test=develop;test=document_fix

* refine print_signatures.py to remove ComposeNotAligned, test=develop

* remove experimental_namespace, test=develop

* fix the api.spec file does not get the class comment problem

* cat new.spec

* check api.spec

* test=develop

add Dygraph api to api.spec

* test=develop

* test=develop

* test=develop

* del #

* Update detection API add new check document

* update API.spec

* test=develop;add shanyi15 approved API.spec

* test=develop;update PM check API.spec

* check api.spec

* test=develop

* update API.spec

* test=develop;update API.spec

* update API.spec

* cat API.spec

* update documnent in api.spec

* check python35 api.spec

* update print_signatures md5 function

* test=develop

* update API.spec

* test=develop;fix python3 API.spec diff

* test=develop

* test=develop

* test=develop

Revert "Merge pull request #14798 from PaddlePaddle/revert-14786-revert-14782-revert-14398-imperative"

This reverts commit b1d3a1c8, reversing
changes made to f1fb64b1.

test=develop

test=develop

test=develop