proposition: Lemma base_heap : all (fun k => k != null) (supp f) -> null \notin supp f.
proof: Proof. by move/allP=>H; apply: (introN idP); move/H. Qed.
imports: Coq(ssreflect ssrbool ssrfun Eqdep) mathcomp(ssrnat eqtype seq path) pcm(options axioms finmap) pcm(pcm unionmap)