proposition: Lemma comp_lfunA f g h : (f \o (g \o h) = (f \o g) \o h)%VF.
proof: Proof. by apply/lfunP=> u; do !rewrite lfunE /=. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)