∀ {α : Type u_1} {σ : Type u_4} [inst : Primcodable α] [inst_1 : Primcodable σ] (f : α → ℕ → σ)
  {g : α → List σ → Option σ},
  Computable₂ g → (∀ (a : α) (n : ℕ), g a (List.map (f a) (List.range n)) = some (f a n)) → Computable₂ f