fact: Definition po_precategory_has_homsets (PO : po X) : has_homsets (po_precategory_ob_mor PO).
imports: UniMath.Foundations.HLevels UniMath.Foundations.Sets UniMath.Foundations.Propositions UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Univalence