∀ {I : Type u_1} {f : I → Type u_2} {γ : Type u_3} [inst : (i : I) → AddZeroClass (f i)] [inst_1 : AddZeroClass γ]
  (g : (i : I) → γ →+ f i) (x y : γ),
  (Pi.addHom fun i => ↑(g i)).toFun (x + y) = (Pi.addHom fun i => ↑(g i)).toFun x + (Pi.addHom fun i => ↑(g i)).toFun y