psychopy/psychopy — pull request #699 by peircej (2014-09-29 09:19:32+00:00)
Title: PEP: values should be compared to None using `is` not `==`

numpy arrays compared this way do an elementwise comparison and in the
future lists/tuples may do the same, using `is` we find out whether the
variable has been set to be None which makes more sense.