racker/falcon — pull request #225 by JustinTArthur (2014-01-24 02:17:14+00:00)
Title: Use `callable` instead of testing for `__call__` attribute in code.

Should be faster, more elegant. See http://stackoverflow.com/questions/16388059/using-callablex-vs-hasattrx-call

Only caveat would be if you want to prevent classes from being passed in these places, given that classes are _callable_ but don't have a `__call__` attribute.