@ ProgramNode (location: (0...27))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...27))
    └── body: (length: 1)
        └── @ UndefNode (location: (0...27))
            ├── names: (length: 3)
            │   ├── @ SymbolNode (location: (6...9))
            │   │   ├── opening_loc: ∅
            │   │   ├── value_loc: (6...9) = "foo"
            │   │   ├── closing_loc: ∅
            │   │   └── unescaped: "foo"
            │   ├── @ SymbolNode (location: (11...15))
            │   │   ├── opening_loc: (11...12) = ":"
            │   │   ├── value_loc: (12...15) = "bar"
            │   │   ├── closing_loc: ∅
            │   │   └── unescaped: "bar"
            │   └── @ InterpolatedSymbolNode (location: (17...27))
            │       ├── opening_loc: (17...19) = ":\""
            │       ├── parts: (length: 2)
            │       │   ├── @ StringNode (location: (19...22))
            │       │   │   ├── opening_loc: ∅
            │       │   │   ├── content_loc: (19...22) = "foo"
            │       │   │   ├── closing_loc: ∅
            │       │   │   └── unescaped: "foo"
            │       │   └── @ EmbeddedStatementsNode (location: (22...26))
            │       │       ├── opening_loc: (22...24) = "\#{"
            │       │       ├── statements:
            │       │       │   @ StatementsNode (location: (24...25))
            │       │       │   └── body: (length: 1)
            │       │       │       └── @ IntegerNode (location: (24...25))
            │       │       │           └── flags: decimal
            │       │       └── closing_loc: (25...26) = "}"
            │       └── closing_loc: (26...27) = "\""
            └── keyword_loc: (0...5) = "undef"
