∀ {α β : Type w} {m : Type w → Type w'} [inst : Std.Iterator α m β] {it' : Std.IterM m β} {out : β}
  {it : Std.IterM m β},
  it.IsPlausibleStep (Std.IterStep.yield it' out) → Std.IterM.IsPlausibleNthOutputStep 0 it (Std.IterStep.yield it' out)