(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)))