yeah, yeah, I know what an assertion is. I have read the same sources as you.
my point is that we're doing a check that the user can have removed during execution.
I *want* to catch that error in production. I *want* to catch it early and explicitely, instead of finding confusing tracebacks that derive from this lack of assertion in production code.

But in any case, if you prefer an assert, let it be it. I'm fed up with bizantine discussions while I have shit to get done.