Boustrophedonic python itertool

boustrophedon.py

#!/usr/bin/env python3
# encoding=utf-8
# vim: set nobomb:

from itertools import chain, cycle, repeat
from typing import Iterable, Iterator, Reversible, TypeVar


T = TypeVar('T')


def boustrophedon(iterator: Iterator[Reversible[T]])\
		-> Iterator[Reversible[T]]:
	"""
	Takes an iterator of (reversible) iterators, returns the
	first element, then returns the second element reversed,
	then the third, then the fourth reversed, and so on.
	"""
	xforms = cycle([lambda it: it, reversed])
	for xform, elem in zip(xforms, iterator):
		yield xform(elem)


def boustrophedon_chained(iterator: Reversible[T], times: int=None)\
		-> Iterable[T]:
	"""
	Used much like itertools.repeat, except it reverses every other
	repetition, and it's chained.
	"""
	if times is None:
		while True:
			yield iterator
			yield reversed(iterator)
	else:
		for i, reverse in zip(range(times), chain.from_iterable(repeat([False, True]))):
			yield reversed(iterator) if reverse else iterator


__all__ = ["boustrophedon", "boustrophedon_chained"]

line #22
Oops, can you tell I don't use repeat much?