fact: Definition J_2_1 {a b : B} {f g : a --> b} (α : invertible_2cell f g) : Y a b f g α := transportf (Y a b f g) (idtoiso_2_1_isotoid_2_1 HB α) (J'_2_1 (isotoid_2_1 HB α)).
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Groupoids UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Univalence UniMath.CategoryTheory.Core.Isos UniMath.Bicategories.Core.Bicat UniMath.Bicategories.Core.Unitors UniMath.Bicategories.Core.Invertible_2cells UniMath.Bicategories.Morphisms.Adjunctions UniMath.Bicategories.Core.BicategoryLaws