∀ {ι : Type v} {β : ι → Type w} [inst : (i : ι) → AddCommMonoid (β i)] [inst_1 : DecidableEq ι] {γ : Type u_1}
  [inst_2 : AddZeroClass γ] ⦃f g : (DirectSum ι fun i => β i) →+ γ⦄,
  (∀ (i : ι), f.comp (DirectSum.of β i) = g.comp (DirectSum.of β i)) → f = g