@ ProgramNode (location: (0...24))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...24))
    └── body: (length: 2)
        ├── @ UndefNode (location: (0...9))
        │   ├── names: (length: 1)
        │   │   └── @ SymbolNode (location: (6...9))
        │   │       ├── opening_loc: ∅
        │   │       ├── value_loc: (6...9) = "foo"
        │   │       ├── closing_loc: ∅
        │   │       └── unescaped: "foo"
        │   └── keyword_loc: (0...5) = "undef"
        └── @ UndefNode (location: (10...24))
            ├── names: (length: 2)
            │   ├── @ SymbolNode (location: (16...19))
            │   │   ├── opening_loc: ∅
            │   │   ├── value_loc: (16...19) = "foo"
            │   │   ├── closing_loc: ∅
            │   │   └── unescaped: "foo"
            │   └── @ SymbolNode (location: (21...24))
            │       ├── opening_loc: ∅
            │       ├── value_loc: (21...24) = "bar"
            │       ├── closing_loc: ∅
            │       └── unescaped: "bar"
            └── keyword_loc: (10...15) = "undef"
