∀ (o : Ordinal.{u_1}) (motive : { x // x ∈ Set.Iio o } → Sort u_2) (x : Ordinal.{u_1}) (property : x ∈ Set.Iio o)
  (h_1 : (x : Ordinal.{u_1}) → (property : x ∈ Set.Iio o) → motive ⟨x, property⟩),
  (match ⟨x, property⟩ with
    | ⟨x, property⟩ => h_1 x property) =
    h_1 x property