'Return the price level for the maximum price
:rtype: PriceLevel'

def get_max_price_list(self, price_wallet_id, quantity_wallet_id):

    key = (price_wallet_id, quantity_wallet_id)
    if ((key in self._depth) and (self._depth[key] > 0)):
        return self.get_price_level(self.get_max_price(price_wallet_id, quantity_wallet_id))
    else:
        return None
