ProgramNode(0...21)(
  [],
  StatementsNode(0...21)(
    [InterpolatedStringNode(0...21)(
       (0...5),
       [StringNode(6...11)(nil, (6...11), nil, "foo\r"),
        EmbeddedVariableNode(11...16)(
          (11...12),
          InstanceVariableReadNode(12...16)()
        ),
        StringNode(16...17)(nil, (16...17), nil, "\n")],
       (17...21)
     )]
  )
)
