ProgramNode(0...16)(
  [],
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    [DefNode(0...16)(
       (4...5),
       nil,
       ParametersNode(6...10)(
         [],
         [],
         [],
         RestParameterNode(6...10)((6...7), (7...10)),
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         nil
       ),
       nil,
       [:foo],
       (0...3),
       nil,
       (5...6),
       (10...11),
       nil,
       (13...16)
     )]
  )
)
