* 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

* add yaml

* perfect converage

* add Logit API

* add unittest

* conflict

* pull conflit

* pull conflit logit

* fix unititest

* fix code style

* update docs style of

* update en doc

* fix docs en style

* fix docs en style1

* fix docs en style2

* fix docs en style3

* fix docs en style4

* fix docs en style5

* fix docs en style6

* fix docs en style7

* fix docs en style8

* update by review

* fix nan bug