This is a built-in module with a lot of useful methods to interface with iterables, which not only improves readability but can improve performance too.
Here are some examples of the built-in functions. More can be found in the docs [1].
With the built-in zip command, when one list is longer than the other and the inputs are exhausted, the rest of the elements in the longer list are discarded. ziplongest can fill in the elements in the shorter list with either None or a specified default value.
list_1 = [1, 2, 3]
list_2 = [4, 5, 6, 7]
print(list(zip(list_1, list_2)))
# [(1, 4), (2, 5), (3, 6)]
from itertools import zip_longest
print(list(zip_longest(list_1, list_2, fillvalue=-1)))
# [(1, 4), (2, 5), (3, 6), (-1, 7)]This repeats a given iterator's items forever, using a generator.
from itertools import cycle
cycler = cycle(["a", "b"])
print([next(cycler) for _ in range(5)])
# ['a', 'b', 'a', 'b', 'a']Return items from an iterator until a given condition evaluates to False.
from itertools import takewhile
the_list = ["a", "b", "x", "y", "fin", "z"]
print(list(takewhile(lambda x: x != "fin", the_list)))[2] Effective Python: 90 Specific Ways to Write Better Python by Brett Slatkin
[3] Python Cookbook, Third Edition by David Beazley and Brian K. Jones
[4] Writing Idiomatic Python 3 by Jeff Knupp