∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] {sq₁ sq₂ : CategoryTheory.Square C}
  (e₁ : sq₁.X₁ ≅ sq₂.X₁) (e₂ : sq₁.X₂ ≅ sq₂.X₂),
  CategoryTheory.CategoryStruct.comp sq₁.f₁₂ e₂.hom = CategoryTheory.CategoryStruct.comp e₁.hom sq₂.f₁₂ →
    CategoryTheory.CategoryStruct.comp sq₁.f₁₂ e₂.hom = CategoryTheory.CategoryStruct.comp e₁.hom sq₂.f₁₂