@ ProgramNode (location: (1,0)-(1,6))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,6))
    └── body: (length: 1)
        └── @ StringNode (location: (1,0)-(1,6))
            ├── flags: ∅
            ├── opening_loc: (1,0)-(1,6) = "<<-END"
            ├── content_loc: (2,0)-(2,0) = ""
            ├── closing_loc: (2,0)-(2,3) = "END"
            └── unescaped: ""