@ ProgramNode (location: (0...5))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...5))
    └── body: (length: 1)
        └── @ InterpolatedStringNode (location: (0...5))
            ├── opening_loc: (0...5) = "<<EOS"
            ├── parts: (length: 3)
            │   ├── @ StringNode (location: (6...11))
            │   │   ├── opening_loc: ∅
            │   │   ├── content_loc: (6...11) = "foo\\r"
            │   │   ├── closing_loc: ∅
            │   │   └── unescaped: "foo\r"
            │   ├── @ EmbeddedVariableNode (location: (11...16))
            │   │   ├── operator_loc: (11...12) = "#"
            │   │   └── variable:
            │   │       @ InstanceVariableReadNode (location: (12...16))
            │   │       └── name: :@bar
            │   └── @ StringNode (location: (16...17))
            │       ├── opening_loc: ∅
            │       ├── content_loc: (16...17) = "\n"
            │       ├── closing_loc: ∅
            │       └── unescaped: "\n"
            └── closing_loc: (17...21) = "EOS\n"
