@ ProgramNode (location: (1,6)-(4,17))
├── locals: [:string]
└── statements:
    @ StatementsNode (location: (1,6)-(4,17))
    └── body: (length: 2)
        ├── @ LocalVariableWriteNode (location: (1,6)-(1,22))
        │   ├── name: :string
        │   ├── depth: 0
        │   ├── name_loc: (1,6)-(1,12) = "string"
        │   ├── value:
        │   │   @ StringNode (location: (1,15)-(1,22))
        │   │   ├── flags: ∅
        │   │   ├── opening_loc: (1,15)-(1,22) = "<<-\"^D\""
        │   │   ├── content_loc: (2,0)-(3,0) = "        very long string\n"
        │   │   ├── closing_loc: (3,0)-(4,0) = "      ^D\n"
        │   │   └── unescaped: "        very long string\n"
        │   └── operator_loc: (1,13)-(1,14) = "="
        └── @ CallNode (location: (4,6)-(4,17))
            ├── flags: ignore_visibility
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── name: :puts
            ├── message_loc: (4,6)-(4,10) = "puts"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (4,11)-(4,17))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ LocalVariableReadNode (location: (4,11)-(4,17))
            │           ├── name: :string
            │           └── depth: 0
            ├── closing_loc: ∅
            └── block: ∅