```
$ git status

Changes not staged for commit:
 (use "git add <file>..." to update what will be committed)
 (use "git checkout -- <file>..." to discard changes in working directory)
       modified:   gulpfile.js


$ git mark debug .

Marked gulpfile.js as debug change

$ git add .

Nothing to add
 (some changes are marked "debug" and weren't added)

$ git status

Changes marked "debug":
 (these changes are marked so they won't be committed or added to the index by "git add <file>")
 (use "git unmark <file>" or "git add --force <file>" to add them to the index)

       modified:   gulpfile.js