For example, coq has in its standard library a Classical package with lemmas in classical logic such as ones that relate forall and exists (https://coq.inria.fr/library/Coq.Logic.Classical_Pred_Type.html).
My question is if there is any support like that in mathcomp or ssreflect itself. All I have found so far is a few definitions and lemmas in https://github.com/coq/stdlib2/blob/master/src/bool.v#L548
Thanks