∀ {α : Type w} {m : Type w → Type w'} {β : Type w} [inst : Monad m] [inst_1 : Std.Iterator α m β]
  [Std.Iterators.Finite α m] {P : β → Std.Iterators.PostconditionT m (ULift.{w, 0} Bool)},
  Std.Iterators.Finite (Std.Iterators.Types.DropWhile α m β P) m