{motive : Lean.Meta.ArrowPropResult✝ → Sort u} →
  (t : Lean.Meta.ArrowPropResult✝¹) →
    motive Lean.Meta.ArrowPropResult.false✝ →
      motive Lean.Meta.ArrowPropResult.true✝ →
        motive Lean.Meta.ArrowPropResult.undef✝ → ((idx : ℕ) → motive (Lean.Meta.ArrowPropResult.bvar✝ idx)) → motive t