A simple code, which explains the process of entity status changing by using of private and public methods.

consumer.py

#!/usr/bin/env python


class Fruit:
    def __init__(self):
        self.__state__ = False

    def isEaten(self):
        return self.__state__

    def consume(self):
        self.__state__ = True


class Person:
    counter = 0

    def eat(self, fruit):
        if not fruit.isEaten():
            fruit.consume()
            self.counter += 1


f1 = Fruit()
f2 = Fruit()

p1 = Person()
p1.eat(f1)
p1.eat(f1)
p1.eat(f2)
print(p1.counter) # should be 2