@ ProgramNode (location: (0...9))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...9))
    └── body: (length: 1)
        └── @ CallNode (location: (0...9))
            ├── receiver:
            │   @ CallNode (location: (0...4))
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── message_loc: (0...4) = "meth"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   ├── block: ∅
            │   ├── flags: variable_call
            │   └── name: "meth"
            ├── call_operator_loc: ∅
            ├── message_loc: (4...6) = "[]"
            ├── opening_loc: (4...5) = "["
            ├── arguments: ∅
            ├── closing_loc: (5...6) = "]"
            ├── block:
            │   @ BlockNode (location: (7...9))
            │   ├── locals: []
            │   ├── parameters: ∅
            │   ├── body: ∅
            │   ├── opening_loc: (7...8) = "{"
            │   └── closing_loc: (8...9) = "}"
            ├── flags: ∅
            └── name: "[]"
