Большой колокольчик

from solution import BigBell
 
bell = BigBell()
bell.sound()
bell.sound()
bell.sound()

class BigBell:
    f = 0
    def sound(self):
        if not self.f :
            print('ding')
            self.f = 1
        else:
            print('dong')
            self.f = 0

#!/usr/bin/env python3
from itertools import cycle
 
 
class BigBell(object):
    def __init__(self):
        self.f = cycle(('ding', 'dong'))
 
    def sound(self):
        print(next(self.f))
 
 
bell = BigBell()
bell.sound()
bell.sound()
bell.sound()

class BigBell:
    def __init__(self):
        self.ding = 'ding'
 
    def sound(self):
        print(self.ding)
        if self.ding == 'ding':
            self.ding = 'dong'
        else:
            self.ding = 'ding'

class BigBell:
    def __init__(self):
        self.a = 0
 
    def sound(self):
        self.a += 1
        if self.a % 2 != 0:
            print('ding')
        else:
            print('dong')

class BigBell:
    def sound(self):
        print(['ding','dong'][bool(BigBell.__doc__)])
        BigBell.__doc__ = not BigBell.__doc__
 
bell = BigBell()
bell.sound()
bell.sound()
bell.sound()

bell = BigBell()
bell2 = BigBell()
 
print(1)
bell.sound()
bell2.sound()
print(2)
 
bell.sound()
bell.sound()