@ ProgramNode (location: (1,0)-(4,6))
├── flags: ∅
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(4,6))
    ├── flags: ∅
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(4,6))
            ├── flags: newline
            ├── receiver:
            │   @ StringNode (location: (1,0)-(1,5))
            │   ├── flags: ∅
            │   ├── opening_loc: (1,0)-(1,5) = "<<END"
            │   ├── content_loc: (2,0)-(3,0) = "blah\n"
            │   ├── closing_loc: (3,0)-(4,0) = "END\n"
            │   └── unescaped: "blah\n"
            ├── call_operator_loc: (4,0)-(4,1) = "."
            ├── name: :strip
            ├── message_loc: (4,1)-(4,6) = "strip"
            ├── opening_loc: ∅
            ├── arguments: ∅
            ├── closing_loc: ∅
            └── block: ∅
