fact: Definition lift_μ : lift_functor ∙ lift_functor ⟹ lift_functor.
imports: UniMath.Foundations.PartD UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.whiskering UniMath.CategoryTheory.Adjunctions.Core UniMath.CategoryTheory.Monads.Monads UniMath.CategoryTheory.Monads.Derivative