fact: Definition rwhisker_CAT {C D E : category} {F1 F2 : [C, D]} (G : [D, E]) : [C, D]⟦F1, F2⟧ -> [C, E]⟦functor_compose F1 G, functor_compose F2 G⟧.
imports: UniMath.Foundations.PartD UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.FunctorCategory UniMath.CategoryTheory.whiskering