∀ {motive : ℕ → ℕ → Sort u_1} (zero_zero : motive 0 0) (zero_succ : (n : ℕ) → motive 0 n → motive 0 (n + 1))
  (succ_zero : (m : ℕ) → motive m 0 → motive (m + 1) 0) (succ_succ : (m n : ℕ) → motive m n → motive (m + 1) (n + 1))
  (n : ℕ),
  Nat.recDiagOn 0 (n + 1) zero_zero zero_succ succ_zero succ_succ =
    zero_succ n (Nat.recDiagOn 0 n zero_zero zero_succ succ_zero succ_succ)