fact: Definition associator_data {C : category} (tu : tensor_unit C) : UU := ∏ x y z : C, C⟦(x ⊗_{tu} y) ⊗_{tu} z, x ⊗_{tu} (y ⊗_{tu} z)⟧.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Isos