{A A' B B' : Type} (h : A + B -> A' + B') (Ha : forall a:A, is_inl (h (inl a))) : inl o unfunctor_sum_l h Ha == h o inl. Proof. intros a; unfold unfunctor_sum_l; apply inl_un_inl. Defined.
Require Import HoTT.Basics. Require Import Types.Empty Types.Unit Types.Prod Types.Sigma. Require Import Types.Bool.