fact: Definition unfunctor_sum_l_beta {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.
imports: HoTT.Basics Types.Empty Types.Unit Types.Prod Types.Sigma Types.Bool Types.Forall