(motive : Lean.Grind.AC.Expr → Sort u_1) →
  (m : Lean.Grind.AC.Expr) →
    ((x : Lean.Grind.AC.Var) → motive (Lean.Grind.AC.Expr.var x)) →
      ((lhs rhs : Lean.Grind.AC.Expr) → motive (lhs.op rhs)) → motive m