fact: Definition id_preserves_associator {C : category} {tu : tensor_unit C} (α : associator tu) : preserves_associator (identity_functor_tensor_unit tu) α α.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Isos