I actually looked at collections.Counter.  It does a whole lot of stuff I never realized beyond just counting, and the class is actually pretty involved at first glance.  In the end I decided porting wasn't worth the time to save 4 lines of trivial code.  Even if it just works out of the box, you have to port the tests, and so on.  If you want to do the port, go for it, but my feeling is that we (you) have higher priorities.

Otherwise it might be worth putting this little counter function in `utils` as a super-lightweight counter.