∀ {α β γ : Type w} {m : Type w → Type w'} {n : Type w → Type w''} [inst : Monad n] [inst_1 : Std.Iterator α m β]
  {lift : ⦃α : Type w⦄ → m α → n α} {f : β → Std.Iterators.PostconditionT n γ} [Std.Iterators.Productive α m],
  Std.Iterators.Productive (Std.Iterators.Types.Map α m n lift f) n