Ref: https://stackoverflow.com/questions/30697324/how-to-check-if-directory-on-path-is-empty.

TODO: Replace below function with stdlib's one when it is merged Ref: https://stackoverflow.com/questions/10485743/contains-method-for-a-slice.

Used only in fetchBookmark.go of`chf` command.

Used in `chs`, `chh`.

InitBookmarkJsonTraversal should be called first before calling this function.