class ZigZagIterator:
    def __init__(self, v1, v2):
        """
        Initialize your data structure here.
        :type v1: List[int]
        :type v2: List[int]
        """
        self.queue=[_ for _ in (v1,v2) if _]
        print(self.queue)

    def next(self):
        """
        :rtype: int
        """
        v=self.queue.pop(0)
        ret=v.pop(0)
        if v: self.queue.append(v)
        return ret

    def has_next(self):
        """
        :rtype: bool
        """
        if self.queue: return True
        return False

l1 = [1, 2]
l2 = [3, 4, 5, 6]
it = ZigZagIterator(l1, l2)
while it.has_next():
    print(it.next())