proposition: Lemma fmU i : U_(i) = [:: i] :> seq I.
proof: Proof. by rewrite fmuE. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap