proposition: Lemma comp_lfunE f g u : (f \o g)%VF u = f (g u).
proof: Proof. exact: lfunE. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)