fact: Definition lan_comma (x : C₂) : category := comma P (constant_functor unit_category _ x).
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Univalence UniMath.CategoryTheory.Adjunctions.Core UniMath.CategoryTheory.Limits.Graphs.Colimits UniMath.CategoryTheory.Categories.StandardCategories UniMath.CategoryTheory.CommaCategories UniMath.CategoryTheory.FunctorCategory UniMath.CategoryTheory.whiskering