Further to Karthikeyan Singaravelan comment, the behaviour you see is absolutely correct. The operator isn't behaving differently, it is reporting precisely the truth.

The ``is`` operator tests for object identity, not equality. Python makes no promises about object identity of literals. If you use an immutable literal in two places:

    a = 1234
    b = 1234

the interpreter is free to use the same object for both a and b, or different objects. The only promise made is that ``a == b``.

The Python interpreter currently caches some small integers for re-use, but that's not a language guarantee, and is subject to change without warning. It has changed in the past, and could change again in the future.

The bottom line is that you shouldn't use ``is`` except to test for object identity, e.g. ``if obj is None``.