∀ {I : Type u} [inst : AddMonoid I] {C : Type u_1} [inst_1 : CategoryTheory.Category.{v_1, u_1} C]
  [inst_2 : CategoryTheory.MonoidalCategory C] (X₁ X₁_1 : CategoryTheory.GradedObject I C) (e_X₁ : X₁ = X₁_1)
  (X₂ X₂_1 : CategoryTheory.GradedObject I C) (e_X₂ : X₂ = X₂_1) [inst_3 : X₁.HasTensor X₂] (a a_1 : I),
  a = a_1 →
    CategoryTheory.GradedObject.Monoidal.tensorObj X₁ X₂ a =
      CategoryTheory.GradedObject.Monoidal.tensorObj X₁_1 X₂_1 a_1