(Program
  (Case
    (Identifier)
    (When
      (Args
      { (Identifier)
      ->(Identifier) })
    { (Identifier)
    ->(When
        (Args
          (Identifier))
        (Args
          (Other "splat_argument"
            (Identifier)))
        (Identifier)
        (Else)) }
    {-(Else
        (Identifier))-})))