@ ProgramNode (location: (0...8))
├── locals: [:c]
└── statements:
    @ StatementsNode (location: (0...8))
    └── body: (length: 1)
        └── @ LocalVariableWriteNode (location: (0...8))
            ├── name: :c
            ├── depth: 0
            ├── name_loc: (0...1) = "c"
            ├── value:
            │   @ CallNode (location: (4...8))
            │   ├── receiver:
            │   │   @ CallNode (location: (4...5))
            │   │   ├── receiver: ∅
            │   │   ├── call_operator_loc: ∅
            │   │   ├── message_loc: (4...5) = "a"
            │   │   ├── opening_loc: ∅
            │   │   ├── arguments: ∅
            │   │   ├── closing_loc: ∅
            │   │   ├── block: ∅
            │   │   ├── flags: variable_call
            │   │   └── name: "a"
            │   ├── call_operator_loc: (5...7) = "&."
            │   ├── message_loc: (7...8) = "b"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   ├── block: ∅
            │   ├── flags: safe_navigation
            │   └── name: "b"
            └── operator_loc: (2...3) = "="
