ProgramNode(0...18)(
  [],
  StatementsNode(0...18)(
    [IfNode(0...18)(
       (0...2),
       IntegerNode(3...4)(),
       nil,
       IfNode(6...13)((6...11), IntegerNode(12...13)(), nil, nil, nil),
       (15...18)
     )]
  )
)
