proposition: Lemma isaprop_isEqualizer' : isaprop isEqualizer'.
proof: Proof. unfold isEqualizer'. apply impred; intro. apply isapropisweq. Qed.
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Univalence UniMath.CategoryTheory.Monics UniMath.CategoryTheory.Retracts