>>> import itertools

>>> a = range(3)
>>> b = range(5)
>>> list(itertools.chain(a, b))
[0, 1, 2, 0, 1, 2, 3, 4]


>>> import itertools

>>> iterables = [range(3), range(5)]
>>> list(itertools.chain.from_iterable(iterables))
[0, 1, 2, 0, 1, 2, 3, 4]