using hobbit to monitor the number of files

Say, in a mail or print spool.  I know hobbit can check the age or existence
of a file, but how about the number of files in a dir?

I'm sure it's trivial to do, but I haven't run across this yet, so before I
reinvent the wheel, I thought I'd ask.

I would like hobbit to report on the number of files in a given location,
and then generate an alert if it's above the warning or fatal levels.

Thanks.