{α : Type} →
  (motive : Lean.Meta.DiscrTree.Key × Lean.Meta.DiscrTree.Trie α → Sort u_1) →
    (x : Lean.Meta.DiscrTree.Key × Lean.Meta.DiscrTree.Trie α) →
      ((fst : Lean.Meta.DiscrTree.Key) → (trie : Lean.Meta.DiscrTree.Trie α) → motive (fst, trie)) → motive x