proposition: Lemma ends_with_a_cons a b l: ends_with_a l a -> ends_with_a (b::l) a.
proof: Proof. by move/eqP => -> /=; rewrite - rcons_cons; apply: ends_with_a_rcons. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype order bigop ssralg) mathcomp(div ssrnum ssrint rat prime path binomial) mathcomp(tuple finset) gaia(fibm)