∀ {α β γ : Type u_1} {m : Type u_1 → Type u_3} {n : Type u_1 → Type u_2} [inst : Monad n] [inst_1 : Std.Iterator α m β]
  {lift : ⦃α : Type u_1⦄ → m α → n α} {f : β → Std.Iterators.PostconditionT n (Option γ)} {it it' : Std.IterM n γ},
  it'.IsPlausibleSuccessorOf it →
    InvImage Std.IterM.IsPlausibleSuccessorOf (Std.Iterators.Types.FilterMap.inner ∘ Std.IterM.internalState) it' it