∀ {R : Type uR} {ι : Type uι} {ι' : Type uι'} {M₂ : Type v₂} [inst : CommSemiring R] [inst_1 : AddCommMonoid M₂]
  [inst_2 : Module R M₂] {N : ι ⊕ ι' → Type u_1} [inst_3 : (i : ι ⊕ ι') → AddCommMonoid (N i)]
  [inst_4 : (i : ι ⊕ ι') → Module R (N i)]
  (g : MultilinearMap R (fun i => N (Sum.inl i)) (MultilinearMap R (fun i => N (Sum.inr i)) M₂)),
  g.uncurrySum.currySum = g