(motive : Lean.Meta.SynthInstanceCacheKey → Sort u_1) →
  (x : Lean.Meta.SynthInstanceCacheKey) →
    ((a : Lean.LocalInstances) →
        (a_1 : Lean.Expr) → (a_2 : ℕ) → motive { localInsts := a, type := a_1, synthPendingDepth := a_2 }) →
      motive x