{motive_1 : Lean.IR.Alt → Sort u} →
  (t : Lean.IR.Alt) →
    ((info : Lean.IR.CtorInfo) → (b : Lean.IR.FnBody) → motive_1 (Lean.IR.Alt.ctor info b)) →
      ((b : Lean.IR.FnBody) → motive_1 (Lean.IR.Alt.default b)) → motive_1 t