def ZigzagIterator(v1,v2):
    ls = []
    while (len(v1) > 0):
        ls.append(v1.pop(0))
        if v2:
            ls.append(v2.pop(0))
    if v2:
        return ls + v2
    return ls

print(ZigzagIterator([1,2,3,4],[5,6,7,8]))