[guscost]

Sure, that's true. But the purpose of asking for the code is because if the program works there is guaranteed to be enough information to reverse-engineer the corresponding model if necessary. With just a specification of a model there may be built-in assumptions involved which only become apparent in the implementation. Standard language and protocols are one way to avoid this problem, but these are usually not as exacting as a compiler.

I'd definitely prefer to have both a model and an implementation available, but if I had to pick just one it would be the code.