Generalize invariant witness
- allows arbitrary expression that ends with the record
- the record doesn't really exists it is replaced by a tuple
- the expression can use effect but it should not be partial
Fixes #286 (closed)
[A venir] Mise en place de quotas sur nos instances gitlab. Pour plus d'information lire: https://doc-si.inria.fr/pages/viewpage.action?pageId=129728565
Fixes #286 (closed)