@ ProgramNode (location: (0...10))
├── locals: [:a, :b]
└── statements:
    @ StatementsNode (location: (0...10))
    └── body: (length: 2)
        ├── @ MultiWriteNode (location: (0...8))
        │   ├── targets: (length: 2)
        │   │   ├── @ LocalVariableTargetNode (location: (0...1))
        │   │   │   ├── name: :a
        │   │   │   └── depth: 0
        │   │   └── @ LocalVariableTargetNode (location: (3...4))
        │   │       ├── name: :b
        │   │       └── depth: 0
        │   ├── lparen_loc: ∅
        │   ├── rparen_loc: ∅
        │   ├── operator_loc: (5...6) = "="
        │   └── value:
        │       @ CallNode (location: (7...8))
        │       ├── receiver: ∅
        │       ├── call_operator_loc: ∅
        │       ├── message_loc: (7...8) = "c"
        │       ├── opening_loc: ∅
        │       ├── arguments: ∅
        │       ├── closing_loc: ∅
        │       ├── block: ∅
        │       ├── flags: variable_call
        │       └── name: "c"
        └── @ CallNode (location: (9...10))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (9...10) = "d"
            ├── opening_loc: ∅
            ├── arguments: ∅
            ├── closing_loc: ∅
            ├── block: ∅
            ├── flags: variable_call
            └── name: "d"
