Class Attributes Inheritance

[Harry_Potter]

Hi All,
I am new to programming & trying to learn python.
I have created Product class(as Parent) & Inventory (as child) class. How can i use attributes declared in product class in inventory class. In the below example i want to use Product attribute 'pcost' in inventory class.
In Cost function i want to do pcost * pnbr.

class Product():
    def __init__(self,pname,pid,pcost):
        self.pname = pname
        self.pid=pid
        self.pcost=pcost
        
class Inventory(Product):
    def __init__(self,pnbr,products):
        Product.__init__(self,pname,pid,pcost)
        self.pnbr=pnbr
    def cost(self):
        self.cost=self.pcost*self.pnbr