class BaniyanProduction:
    def __init__(self, production, sold, full=0):
        self.production = production
        self.sold = sold
        self.full = 0
        #self.profit = 0 ## if you want to use self.var you must put it here

    #def profit(self, profit): #you never defined what profit was, you would have to run BP.pofit(profit) with profit being a defined int
    def profit(self):
        this_profit = self.full+self.sold #dont need self.profit as its a local variable
        return this_profit

    def loss(self):
        this_loss = self.production-self.sold
        return this_loss

    def nothing(self):
        return "invalid" ##return statmet would be better than printing

self_p = int(input('production:>'))
self_s = int(input('sold:>'))
BP = BaniyanProduction(self_p, self_s)
##notice i do not need to specify what full should be as you already defaulted it to 0, however i can overwrite it if needed
#now the BP class has set self.production and self.sold to self_p and self_s and will stay like that unless you modify them in the class


#while True: #this will run it with the same arguments over and over
if self_p == self_s:
    print(BP.profit()) ##dont need any extra vars here as you put theim in __init__ already
elif self_s<self_p:
    print(BP.loss())
else:
    print(BP.nothing()) ##this is why we returned the string. Not needed but makes it cleaner.