proposition: Lemma fresh_dom h : fresh h \notin dom h.
proof: Proof. by move: (dom_freshn h 0); rewrite addn0. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path interval) pcm(options prelude pred finmap rtc seqext useqord uslice uconsec)