* Replace itertools.ifilter() with six.moves.filter()
* Replace itertools.imap() with six.moves.map()
* Replace map(_compare, statistics)
with [_compare(statistic) for statistic in statistics]
* Replace obj.iterkeys() with six.iterkeys(obj)
* Replace obj.iteritems() with six.iteritems(obj)
* Replace xrange() with six.moves.xrange(), or with range() for small
ranges
* Replace the repr module with six.moves.reprlib
Change-Id: Iaaa328cc15355182bde444a1aeaa4385691c8f90
de9c4891e7