Failing to import itertools in Python 3.5.2

izip_longest was renamed to zip_longest in Python 3 (note, no i at the start), import that instead:

from itertools import zip_longest

and use that name in your code.

If you need to write code that works both on Python 2 and 3, catch the ImportError to try the other name, then rename:

try:
    # Python 3
    from itertools import zip_longest
except ImportError:
    # Python 2
    from itertools import izip_longest as zip_longest

# use the name zip_longest