∀ {α β : Type u_1} {IsPlausibleStep : Std.IterM Id β → Std.IterStep (Std.IterM Id β) β → Prop}
  {step : (it : Std.IterM Id β) → Id (Std.Shrink (Std.PlausibleIterStep (IsPlausibleStep it)))} {it : Std.Iter β},
  it.step = Std.IterM.Step.toPure (step it.toIterM).run.inflate