GitLab

* refactor the function and module of laplacian_pe

* add blank lines between design doc

* 1st approving review

* update the unittest

* fix lint issues

* fix trailing space

* update by mufei's comments and fix backend bugs

* del test file
Co-authored-by: rudongyu <ru_dongyu@outlook.com>
Co-authored-by: Rhett Ying <85214957+Rhett-Ying@users.noreply.github.com>