∀ {α : Type u_1} {β : Type u_2} {γ : Type u_3} {σ : Type u_4} [inst : Primcodable α] [inst_1 : Primcodable β]
  [inst_2 : Primcodable γ] [inst_3 : Primcodable σ] {f : α → β ⊕ γ} {g : α → β → σ} {h : α → γ → σ},
  Computable f → Computable₂ g → Computable₂ h → Computable fun a => Sum.casesOn (f a) (g a) (h a)