∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] {B A : C} (X : CategoryTheory.Subobject B) (f : A ⟶ B)
  [inst_1 : CategoryTheory.Mono f] (h : X ≤ CategoryTheory.Subobject.mk f),
  X.ofLEMk f h =
    CategoryTheory.CategoryStruct.comp (X.ofLE (CategoryTheory.Subobject.mk f) h)
      (CategoryTheory.Subobject.underlyingIso f).hom