∀ {Ω : Type u_1} {ι : Type u_2} {m : MeasurableSpace Ω} [inst : Preorder ι] {β : Type u_3} [inst_1 : TopologicalSpace β]
  [inst_2 : MeasurableSpace ι] (f : MeasureTheory.Filtration ι m) (b : β), MeasureTheory.ProgMeasurable f fun x x_1 => b