def __init__(self, iter=[]):
    self.stack_one = s()
    self.stack_two = s()
    self._len = 0
    for item in iter:
        self.enqueue(item)
def __init__(self, iter=[]):
    self.stack_one = s()
    self.stack_two = s()
    self._len = 0
    for item in iter:
        self.enqueue(item)