In 14 500 500 In 15 is Out 15 True In 16 500 In 17 500 In 18 is Out 18

In [14]: a, b = 500, 500

In [15]: a is b
Out[15]: True

In [16]: a = 500

In [17]: b = 500

In [18]: a is b
Out[18]: False

In [22]: b = 200

In [23]: a = 200

In [24]: a is b
Out[24]: True