Code review comment for lp:~mikemc/dirspec/add-exefind

This is more what I was thinking, in terms of having a 'smarter' API, that we could just use via kwargs, and simply state in the docstring what kwargs are available for use, though they aren't required: http://bazaar.launchpad.net/~dobey/dirspec/add-exefind/revision/12

I haven't updated the docstring in that revision, but there are the fallback_dirs= and app_names= kwargs, to specify a list of fallback directories, and a dict of app names for darwin.