proposition: Lemma doubleq (x: rat): x *2%:Q = x + x.
proof: Proof. by rewrite - mulr2n mulr_natr. 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)