(Program
  (Call
    (Identifier)
  {+(Identifier)+}
    (Identifier)
  {-(Identifier)-}
    (Empty))
  (Call
    (Identifier)
  {+(Identifier)+}
  {-(Identifier)-}
    (Empty))
  (Call
    (Identifier)
    (Or
      (Integer)
      (
        (Integer)))
    (Empty))
  (Call
    (Identifier)
  {-(Or
      (Integer)
      (
        (Integer)))-}
    (Or
      (Integer)
      (
        (Integer)))
  {+(Or
      (Integer)
      (
        (Integer)))+}
    (Empty)))