proposition: Lemma is_set_sub_precategory_morphisms {C : category} (C' : sub_precategories C) (a b : ob C) : isaset (sub_precategory_morphisms C' a b).
proof: Proof. apply isofhlevel_hsubtype, C. Defined.
imports: UniMath.Foundations.Sets UniMath.MoreFoundations.PartA UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.Isos