chain_pop.py

def take(iterable, num):
    for i, elem in enumerate(iterable):
        yield elem
        if i  + 1 == num:
            break

def chain_pop(*iterable):
    for elem in iterable:
        while True:
            try:
                el = elem.pop()
                yield el
            except IndexError:
                break

l1 = ['a', 'b', 'c']
l2 = ['d', 'e', 'f']
l3 = ['g', 'h', 'i']

print [el for el in chain_pop(l1, l2, l3)]

l1 = ['a', 'b', 'c']
l2 = ['d', 'e', 'f']
l3 = ['g', 'h', 'i']

print [el for el in take(chain_pop(l1, l2, l3), 4)]
print l1, l2, l3