∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {X Y : C} {f g : X ⟶ Y}
  [inst_1 : CategoryTheory.Limits.HasEqualizer f g] {W : C} {k l : W ⟶ CategoryTheory.Limits.equalizer f g},
  k = l ↔
    CategoryTheory.CategoryStruct.comp k (CategoryTheory.Limits.equalizer.ι f g) =
      CategoryTheory.CategoryStruct.comp l (CategoryTheory.Limits.equalizer.ι f g)