fact: Definition SingletonArrow (B : C) : C⟦ B , (PowerObject_on_ob P) B⟧.
imports: UniMath.Foundations.PartD UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Limits.Terminal UniMath.CategoryTheory.Limits.Pullbacks UniMath.CategoryTheory.Limits.BinProducts UniMath.CategoryTheory.SubobjectClassifier UniMath.CategoryTheory.exponentials UniMath.CategoryTheory.PowerObject UniMath.CategoryTheory.Monics UniMath.CategoryTheory.exponentials UniMath.CategoryTheory.Adjunctions.Core UniMath.CategoryTheory.Subobjects UniMath.CategoryTheory.opp_precat UniMath.CategoryTheory.Categories.HSET.MonoEpiIso