∀ {α : Type u} {β : Type v} (s : Stream'.Seq α) (f g : Stream'.Seq α → Stream'.Seq β),
  (∀ (s : Stream'.Seq α), Stream'.Seq.BisimO (fun s1 s2 => ∃ s, s1 = f s ∧ s2 = g s) (f s).destruct (g s).destruct) →
    f s = g s