It is defined above:

https://github.com/typesafehub/angular-seed-play/pull/7/files#diff-f5260081ec80c28a01bd5809279dbfa4L7

I've found it good practice to do this in order to:

* not have webjars! throughout my code (and thus keep it portable); and
* have the module return something that makes sense rather than rely on globals throughout my code.