∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] (self : CategoryTheory.Monad C) (X : C) {Z : C}
  (h : self.obj X ⟶ Z),
  CategoryTheory.CategoryStruct.comp (self.map (self.η.app X)) (CategoryTheory.CategoryStruct.comp (self.μ.app X) h) = h