classes.py

class Building:

    __matherial = None
    __color = None
    __quantity = 0

    def __init__(self, matherial, color, number = 0):
        self.__matherial = matherial
        self.__color = color
        self.__quantity = number
    
    def place(self):
        if self.__quantity <= 0:
            return 'out of stock'
        elif 0 < self.__quantity <= 100:
            return 'warehouse'
        else:
            return 'remote warehouse'

b1 = Building('iron', 'gray', 100)
b2 = Building('brick', 'red', 50)
b3 = Building('wood', 'green', 1500)
b4 = Building('silver', 'grey')

print(b1.place())
print(b2.place())
print(b3.place())
print(b4.place())