@ ProgramNode (location: (1,0)-(3,1))
├── flags: ∅
├── locals: [:a, :b]
└── statements:
    @ StatementsNode (location: (1,0)-(3,1))
    ├── flags: ∅
    └── body: (length: 2)
        ├── @ MultiWriteNode (location: (1,0)-(2,5))
        │   ├── flags: newline
        │   ├── lefts: (length: 2)
        │   │   ├── @ LocalVariableTargetNode (location: (1,0)-(1,1))
        │   │   │   ├── flags: ∅
        │   │   │   ├── name: :a
        │   │   │   └── depth: 0
        │   │   └── @ LocalVariableTargetNode (location: (2,0)-(2,1))
        │   │       ├── flags: ∅
        │   │       ├── name: :b
        │   │       └── depth: 0
        │   ├── rest: ∅
        │   ├── rights: (length: 0)
        │   ├── lparen_loc: ∅
        │   ├── rparen_loc: ∅
        │   ├── operator_loc: (2,2)-(2,3) = "="
        │   └── value:
        │       @ CallNode (location: (2,4)-(2,5))
        │       ├── flags: variable_call, ignore_visibility
        │       ├── receiver: ∅
        │       ├── call_operator_loc: ∅
        │       ├── name: :c
        │       ├── message_loc: (2,4)-(2,5) = "c"
        │       ├── opening_loc: ∅
        │       ├── arguments: ∅
        │       ├── closing_loc: ∅
        │       └── block: ∅
        └── @ CallNode (location: (3,0)-(3,1))
            ├── flags: newline, variable_call, ignore_visibility
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── name: :d
            ├── message_loc: (3,0)-(3,1) = "d"
            ├── opening_loc: ∅
            ├── arguments: ∅
            ├── closing_loc: ∅
            └── block: ∅
