proposition: Lemma tetakeK (T : eqType) (m : nat) (t1 t2 : m.-tuple T) : tetake (teocat t1 t2) = t1.
proof: Proof. by apply/val_eqP; rewrite /= tetakeE /= etake_eocat. Qed.
imports: mathcomp(all_ssreflect perm algebra.zmodp) mathcomp(zify)