GitLab

* add seal example

* 1. add paper infomation in examples/README
2. adjust codes
3. option test

* use latest `to_simple` to replace coalesce graph function

* remove outdated codes

* remove useless comment

* Node2vec
1.implement node2vec random walk c++ op
2.implement node2vec model
3.implement node2vec example

* add CMakeLists file modify

* refine c++ codes

* refine c++ codes

* add missing whitespace

* refine python codes

* add codes

* add node2vec_impl.h

* fix codes

* fix code style problem

* fixes

* remove

* lots of changes

* add benchmark

* fixes
Co-authored-by: smilexuhc <smile.xuhc@gmail.com>
Co-authored-by: Minjie Wang <wmjlyjemaine@gmail.com>