(Program
  (Function
    (Empty)
    (Empty)
    (Empty)
  {-(RequiredParameter
    {-(Empty)-}
    {-(Empty)-}
    {-(Assignment
      {-(Identifier)-}
      {-(Empty)-})-})-}
    (RequiredParameter
      (Empty)
      (Empty)
      (Assignment
        (Identifier)
        (Empty)))
  {+(RequiredParameter
    {+(Empty)+}
    {+(Empty)+}
    {+(Assignment
      {+(Identifier)+}
      {+(Empty)+})+})+}
    (
      (Return
      { (Plus
        {-(Identifier)-}
        {-(Identifier)-})
      ->(Times
        {+(Identifier)+}
        {+(Identifier)+}) }))))