fact: Definition pb_obj {b₁ b₂ b₃ : B} (f : b₁ --> b₃) (g : b₂ --> b₃) : B := pr1 (pr2 B _ _ _ f g).
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.Bicategories.Core.Bicat UniMath.Bicategories.Core.Unitors UniMath.Bicategories.Core.BicategoryLaws UniMath.Bicategories.Core.Invertible_2cells UniMath.Bicategories.Limits.Pullbacks