Простой пример __getitem__ и __setitem__

# -*- coding: utf-8 -*-

class MyArray():

    def __init__(self):
        self._range = range(5, 10)

    def __getitem__(self, key):
        return self._range[key]

    def __setitem__(self, key, value):
        self._range[key] = value

if __name__ == "__main__":
    f = MyArray()
    print f[2]
    f[2] = 0
    print f[2]