{C : Type u₁} →
  [inst : CategoryTheory.Category.{v₁, u₁} C] →
    {B A : C} →
      (f : A ⟶ B) →
        [inst_1 : CategoryTheory.Mono f] →
          (X : CategoryTheory.Subobject B) →
            CategoryTheory.Subobject.mk f ≤ X → (A ⟶ CategoryTheory.Subobject.underlying.obj X)