chunker.py

from itertools import islice, chain


class Chunk:
    def __init__(self, iterator, size):
        self._iterator = chain([next(iterator)], islice(iterator, size-1))

    def __next__(self):
        return next(self._iterator)

    def __iter__(self):
        return self

    def exhaust(self):
        self._iterator = iter(list(self._iterator))


def chunk(xs, size):
    iterator = iter(xs)
    current = Chunk(iterator, size)
    while True:
        yield current
        current.exhaust()
        current = Chunk(iterator, size)