∀ {α : Type u_2} {β : Type u_1} [inst : Group α] [inst_1 : Group β] (e : WithZero α ≃* WithZero β) (x y : α),
  { toFun := fun x => WithZero.unzero ⋯, invFun := fun x => WithZero.unzero ⋯, left_inv := ⋯, right_inv := ⋯ }.toFun
      (x * y) =
    { toFun := fun x => WithZero.unzero ⋯, invFun := fun x => WithZero.unzero ⋯, left_inv := ⋯, right_inv := ⋯ }.toFun
        x *
      { toFun := fun x => WithZero.unzero ⋯, invFun := fun x => WithZero.unzero ⋯, left_inv := ⋯, right_inv := ⋯ }.toFun
        y