ProgramNode(0...8)(
  [],
  StatementsNode(0...8)(
    [InterpolatedStringNode(0...8)(
       (0...1),
       [EmbeddedStatementsNode(1...5)(
          (1...3),
          StatementsNode(3...4)(
            [CallNode(3...4)(nil, nil, (3...4), nil, nil, nil, nil, 0, "a")]
          ),
          (4...5)
        ),
        StringNode(5...7)(nil, (5...7), nil, " b")],
       (7...8)
     )]
  )
)
