(Program
  (Call
    (Identifier)
    (Identifier)
    (Identifier)
    (Empty))
  (Call
    (Identifier)
    (Identifier)
    (Empty))
  (Call
    (Identifier)
    (Or
      (Integer)
      (Integer))
    (Empty))
  (Call
    (Identifier)
    (Or
      (Integer)
      (Integer))
    (Or
      (Integer)
      (Integer))
    (Empty)))