(Program
  (Package
    (Identifier))
  (Function
    (Empty)
    (Identifier)
    ([])
    (Assignment
      (Identifier)
      (Function
        (Empty)
        (Empty)
        (
          (Identifier)
          (Identifier))
        (
          (
            (Identifier))
          (
            (Identifier)))
        (Return
          (
            (Integer)
            (Integer)))))))