def subscribe_price(self, prod_code):
    self._price_queues.setdefault(prod_code, deque(maxlen=1))
    subscribe_price(prod_code, 1)
def subscribe_price(self, prod_code):
    self._price_queues.setdefault(prod_code, deque(maxlen=1))
    subscribe_price(prod_code, 1)