@ ProgramNode (location: (0...11))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...11))
    └── body: (length: 1)
        └── @ CallNode (location: (0...11))
            ├── receiver:
            │   @ CallNode (location: (0...3))
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── message_loc: (0...3) = "foo"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   ├── block: ∅
            │   ├── flags: variable_call
            │   └── name: "foo"
            ├── call_operator_loc: (3...5) = "&."
            ├── message_loc: (5...8) = "bar"
            ├── opening_loc: ∅
            ├── arguments: ∅
            ├── closing_loc: ∅
            ├── block:
            │   @ BlockNode (location: (9...11))
            │   ├── locals: []
            │   ├── parameters: ∅
            │   ├── body: ∅
            │   ├── opening_loc: (9...10) = "{"
            │   └── closing_loc: (10...11) = "}"
            ├── flags: safe_navigation
            └── name: "bar"
