fact: Definition kleisli_monad_nat_trans {C : category} (m : Monad C) : m ∙ Left_Kleisli_functor m ⟹ Left_Kleisli_functor m.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Adjunctions.Core UniMath.CategoryTheory.Monads.Monads UniMath.CategoryTheory.whiskering