[heykav]

inspect.signature(compose(max, f)) raises ValueError: no signature found for builtin max even though f has a perfectly good signature. Compose.__signature__ only uses the last function for the return annotation, so I wrapped that lookup in a try/except and fall back to no return annotation.

I added a test that uses max as the last function. It fails before the change and passes after, and the existing tests still pass.

[Wkhanex]

Checked 198e202 on CPython 3.12.14 with two non-introspectable final callables: builtin max (ValueError from inspection) and a callable whose __signature__ raises TypeError. In both cases, composition still ran correctly and retained every input parameter's kind, annotation and default, including positional-only, variadic and keyword-only parameters; the return annotation was empty as intended.

I also checked that an inspectable final callable keeps its return annotation and that a non-introspectable input callable still raises instead of fabricating a parameter signature. All 8 assertions passed; the base fails on max. The existing compose tests passed with 5 passed and 1 skipped. Full-suite and version-matrix coverage were not run.

Review prepared with Codex assistance; the checks described above were executed locally.