@ ProgramNode (location: (1,0)-(1,2))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,2))
    └── body: (length: 1)
        └── @ StringNode (location: (1,0)-(1,2))
            ├── flags: ∅
            ├── opening_loc: (1,0)-(1,1) = "?"
            ├── content_loc: (1,1)-(1,2) = "a"
            ├── closing_loc: ∅
            └── unescaped: "a"
