proposition: Lemma dom_cond k f : k \in dom f -> C k.
proof: Proof. by rewrite !umEX; case: (UMC.from f)=>[|f' F] // /(allP F). Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)