@ ProgramNode (location: (0...6))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...6))
    └── body: (length: 1)
        └── @ RegularExpressionNode (location: (0...6))
            ├── opening_loc: (0...3) = "%r'"
            ├── content_loc: (3...5) = "\\'"
            ├── closing_loc: (5...6) = "'"
            ├── unescaped: "'"
            └── flags: ∅
