ProgramNode(0...32)(
  [],
  StatementsNode(0...32)(
    [DefNode(0...32)(
       (9...13),
       SelfNode(4...8)(),
       ParametersNode(14...17)(
         [RequiredParameterNode(14...17)(:cmd)],
         [],
         [],
         nil,
         [],
         nil,
         nil
       ),
       StatementsNode(21...32)(
         [CallNode(21...32)(
            nil,
            nil,
            (21...27),
            (27...28),
            ArgumentsNode(28...31)([LocalVariableReadNode(28...31)(:cmd, 0)]),
            (31...32),
            nil,
            0,
            "system"
          )]
       ),
       [:cmd],
       (0...3),
       (8...9),
       (13...14),
       (17...18),
       (19...20),
       nil
     )]
  )
)
