@ ProgramNode (location: (0...6))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...6))
    └── body: (length: 1)
        └── @ StringNode (location: (0...6))
            ├── opening_loc: (0...6) = "<<~FOO"
            ├── content_loc: (7...20) = "  baz\\\n  qux\n"
            ├── closing_loc: (20...24) = "FOO\n"
            └── unescaped: "bazqux\n"
