class Goods():
    def __init__(self):
        self._price = ""

    @property
    def price(self):
        return self._price

    @price.setter
    def price(self, value):
        self._price = value

    @price.deleter
    def price(self):
        del self._price

g = Goods()
a = g.price
print(a)

g.price = 123
b = g.price
print(b)

del g.price