∀ (s : String) (motive : Char → Option (s.Pos × ℕ) → Sort u_1) (x : Char) (x_1 : Option (s.Pos × ℕ))
  (h_1 : (q : s.Pos) → (v : ℕ) → x_1 = some (q, v) → motive 'u' (some (q, v)))
  (h_2 : (x : Char) → (x_2 : Option (s.Pos × ℕ)) → x_1 = x_2 → motive x x_2),
  (∀ (q : s.Pos) (v : ℕ), x = 'u' → x_1 = some (q, v) → False) →
    (match x, h₂ : x_1 with
      | 'u', some (q, v) => h_1 q v h₂
      | x, x_3 => h_2 x x_3 h₂) =
      h_2 x x_1 ⋯