(Program
  (Comprehension
  { (Identifier)
  ->(Identifier) }
    (
      (
        (
        { (Identifier)
        ->(Identifier) })
      { (Identifier)
      ->(Identifier) })))
  (Comprehension
  { (Identifier)
  ->(Plus
    {+(Identifier)+}
    {+(Integer)+}) }
    (
      (
        (
        { (Identifier)
        ->(Identifier) })
      { (Identifier)
      ->(Identifier) }))))