proposition: Corollary nat_comp_assoc C D (F G H J : C ⟶ D) (M : H ⟹ J) (N : G ⟹ H) (O : F ⟹ G) : M ∙ (N ∙ O) ≈[Fun] (M ∙ N) ∙ O.
proof: Proof. unfold nat_compose; simpl; intros; cat. Qed.
imports: Category.Lib Category.Theory.Category Category.Theory.Isomorphism Category.Theory.Functor Category.Theory.Natural.Transformation Category.Instance.Sets