ah, yes, loc_mapper() is a global function defined in xmodule.modulestore.django. This file is somewhat demonstrative of how to use it; thus, accessing it as if it were the one defined in django w/o requiring django.

btw: I couldn't figure out how to patch, mock, or whatever the one in django w/o causing the django module to load and thus bring in the django dependencies. If you know how, that would be better than what I'm doing here.