Uses itertools to add an "unravel" function...unravel takes iterables and cycles through them yielding the first element until all the elements are gone, or until a limit is reached.

unravel.py

import itertools

def unravel(*iterables, limit = None):
	yield from itertools.islice(
		filter(None,
			itertools.chain.from_iterable(
				itertools.zip_longest(
					*iterables))), limit)
					
# a = [x for x in range(10)]
# b = [x for x in range(5)]
# c = [x for x in range(0, 20, 2)]
# d = [x for x in range(1, 30, 2)]
# print(list(unravel(a, b)))
# print(list(unravel(a, b, limit = 3)))
# print(list(unravel(a, b, c, d, limit = 20)))