ProgramNode(0...24)(
  [:a],
  StatementsNode(0...24)(
    [LocalVariableOperatorAndWriteNode(0...7)(
       (0...1),
       (2...5),
       CallNode(6...7)(nil, nil, (6...7), nil, nil, nil, nil, 0, "b"),
       :a
     ),
     LocalVariableOperatorWriteNode(9...15)(
       (9...10),
       (11...13),
       CallNode(14...15)(nil, nil, (14...15), nil, nil, nil, nil, 0, "b"),
       :a,
       :+
     ),
     LocalVariableOperatorOrWriteNode(17...24)(
       (17...18),
       (19...22),
       CallNode(23...24)(nil, nil, (23...24), nil, nil, nil, nil, 0, "b"),
       :a
     )]
  )
)
