proposition: Lemma heapE pf pg : f = g <-> @Def f pf = @Def g pg.
proof: Proof. split=>[E|[//]]; move: pf pg. by rewrite E=>pf pg; congr Def; apply: bool_irrelevance. Qed.
imports: mathcomp(ssreflect ssrfun ssrnat div ssrbool seq) LemmaOverloading(prelude finmap ordtype) mathcomp(path eqtype) Eqdep