@ ProgramNode (location: (0...9))
├── locals: [:s]
└── statements:
    @ StatementsNode (location: (0...9))
    └── body: (length: 1)
        └── @ LocalVariableWriteNode (location: (0...9))
            ├── name: :s
            ├── depth: 0
            ├── name_loc: (0...1) = "s"
            ├── value:
            │   @ StringNode (location: (4...9))
            │   ├── opening_loc: (4...9) = "<<eos"
            │   ├── content_loc: (10...17) = "a\\xE9b\n"
            │   ├── closing_loc: (17...21) = "eos\n"
            │   └── unescaped: "a\xE9b\n"
            └── operator_loc: (2...3) = "="
