Add a note explaining why you shouldn't try to compute mean and standard deviation.  Also add an XXX comment wondering if we should refrain from using itertools.repeat().
Add a note explaining why you shouldn't try to compute mean and
standard deviation.  Also add an XXX comment wondering if we should
refrain from using itertools.repeat().

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator