But that's what I am saying. Please check the sample tests. Whatever the two tests (failing) are expecting is what my code is giving as outputs. The error thrown says the opposite.

Thanks for that.
A quick one before you go. I am still getting my hands dirty with all this. Could you send a resource on this input mutation. I am not sure I understand what is meant and could not find any resource that quite explained it well. I came across it in another kata I was doing and didn't finish it as it was the only test failing.
Thanks.

My implementation in Python fails one of the basic tests yet outputs exactly what is expected from the failing test. Any assistance?