1639.lean:17:4: error: unify tactic failed, failed to unify
  ?m_1
  : ?m_2 =
    let k : ℕ :=
          (let k : ℕ :=
                   (let k : ℕ :=
                            (let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                   k : ℕ := k + k
                               in k) +
                              let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                  k : ℕ := k + k
                              in k,
                          k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                          k : ℕ := k + k
                      in k) +
                     let k : ℕ :=
                           (let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                  k : ℕ := k + k
                              in k) +
                             let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                 k : ℕ := k + k
                             in k,
                         k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                         k : ℕ := k + k
                     in k,
                 k : ℕ :=
                   (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
                     let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                         k : ℕ := k + k
                     in k,
                 k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                 k : ℕ := k + k
             in k) +
            let k : ℕ :=
                  (let k : ℕ :=
                           (let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                  k : ℕ := k + k
                              in k) +
                             let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                 k : ℕ := k + k
                             in k,
                         k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                         k : ℕ := k + k
                     in k) +
                    let k : ℕ :=
                          (let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                 k : ℕ := k + k
                             in k) +
                            let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                k : ℕ := k + k
                            in k,
                        k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                        k : ℕ := k + k
                    in k,
                k : ℕ :=
                  (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
                    let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                        k : ℕ := k + k
                    in k,
                k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                k : ℕ := k + k
            in k,
        k : ℕ :=
          (let k : ℕ :=
                   (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
                     let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                         k : ℕ := k + k
                     in k,
                 k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                 k : ℕ := k + k
             in k) +
            let k : ℕ :=
                  (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
                    let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                        k : ℕ := k + k
                    in k,
                k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                k : ℕ := k + k
            in k,
        k : ℕ :=
          (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
            let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                k : ℕ := k + k
            in k,
        k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
        k : ℕ := k + k
    in k
and
  1 : ℕ
state:
n : ℕ
⊢ ?m_1 =
    let k : ℕ :=
          (let k : ℕ :=
                   (let k : ℕ :=
                            (let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                   k : ℕ := k + k
                               in k) +
                              let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                  k : ℕ := k + k
                              in k,
                          k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                          k : ℕ := k + k
                      in k) +
                     let k : ℕ :=
                           (let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                  k : ℕ := k + k
                              in k) +
                             let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                 k : ℕ := k + k
                             in k,
                         k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                         k : ℕ := k + k
                     in k,
                 k : ℕ :=
                   (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
                     let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                         k : ℕ := k + k
                     in k,
                 k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                 k : ℕ := k + k
             in k) +
            let k : ℕ :=
                  (let k : ℕ :=
                           (let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                  k : ℕ := k + k
                              in k) +
                             let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                 k : ℕ := k + k
                             in k,
                         k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                         k : ℕ := k + k
                     in k) +
                    let k : ℕ :=
                          (let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                 k : ℕ := k + k
                             in k) +
                            let k : ℕ := (let k : ℕ := n + n in k) + let k : ℕ := n + n in k,
                                k : ℕ := k + k
                            in k,
                        k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                        k : ℕ := k + k
                    in k,
                k : ℕ :=
                  (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
                    let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                        k : ℕ := k + k
                    in k,
                k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                k : ℕ := k + k
            in k,
        k : ℕ :=
          (let k : ℕ :=
                   (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
                     let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                         k : ℕ := k + k
                     in k,
                 k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                 k : ℕ := k + k
             in k) +
            let k : ℕ :=
                  (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
                    let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                        k : ℕ := k + k
                    in k,
                k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                k : ℕ := k + k
            in k,
        k : ℕ :=
          (let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k, k : ℕ := k + k in k) +
            let k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
                k : ℕ := k + k
            in k,
        k : ℕ := (let k : ℕ := k + k in k) + let k : ℕ := k + k in k,
        k : ℕ := k + k
    in k
