Adds callable object test to testfilter
Adds callable object test to testfilter

tempbottle/cppitertools,jkhoogland/cppitertools,tempbottle/cppitertools,tempbottle/cppitertools,ryanhaining/cppitertools,ryanhaining/cppitertools,jkhoogland/cppitertools,jkhoogland/cppitertools,ryanhaining/cppitertools