fact: Definition right_unitor_to_nat_trans (ρ' : right_unitor): nat_trans I_posttensor (functor_identity C) := nat_z_iso_to_trans ρ'.
imports: UniMath.Foundations.PartD UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.ProductCategory UniMath.CategoryTheory.PrecategoryBinProduct UniMath.CategoryTheory.whiskering