Lean.Compiler.LCNF.Arg Lean.Compiler.LCNF.Purity.impure →
  Lean.Expr →
    (Lean.Compiler.LCNF.Arg Lean.Compiler.LCNF.Purity.impure →
        Lean.Compiler.LCNF.BoxM✝ (Lean.Compiler.LCNF.Code Lean.Compiler.LCNF.Purity.impure)) →
      Lean.Compiler.LCNF.BoxM✝¹ (Lean.Compiler.LCNF.Code Lean.Compiler.LCNF.Purity.impure)