proposition: Lemma limit_pr1 x: (x == zero) (+) (T1limit x (+) T1is_succ x).
proof: Proof. elim: x => //a _ n b Hb /=; case az: (a== zero) => //. by case bz: (b == zero); [ rewrite (eqP bz) | move: Hb; rewrite bz]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(fintype bigop)