proposition: Lemma umcnt_predT f : um_count predT f = size (dom f).
proof: Proof. by rewrite /um_count umfilt_predT. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)