You've elided some cases, which I'm guessing don't fit Python's assert so well. And what are foo/bar/zot/pi in your translation? Python has "is"/"not"/"in" which retain some of the English-ness, so my example wasn't totally foreign, but...

You should also know that, unlike "assert" in Python, "ascertain" is not something defined by the Common Lisp language. It was defined by a Common Lisp user (me), just some 50-line macro that can be extended at will, to fit whatever clauses I would like it to support, in any way I see fit.

I'm glad that you took a stab at answering my question, but I hope you can see my point more clearly - that in Lisp you can taylor the language to suit your needs, and while sometimes Python may provide similar syntax, other times it may not. In fact many operators already existing in Common Lisp have no direct correspondence. You can also find tons more examples in the code of other people.

Anyway, hope it at least piqued your interest. Have a good day!