fact: Definition Under_precategories_mor_ob {c c' : C} (h : C⟦c, c'⟧) : c' / C → c / C.
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors