@ ProgramNode (location: (0...16))
├── locals: [:a]
└── statements:
    @ StatementsNode (location: (0...16))
    └── body: (length: 1)
        └── @ LocalVariableWriteNode (location: (0...16))
            ├── name: :a
            ├── depth: 0
            ├── name_loc: (0...1) = "a"
            ├── value:
            │   @ CallNode (location: (4...16))
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── message_loc: (4...5) = "b"
            │   ├── opening_loc: ∅
            │   ├── arguments:
            │   │   @ ArgumentsNode (location: (6...16))
            │   │   └── arguments: (length: 1)
            │   │       └── @ RescueModifierNode (location: (6...16))
            │   │           ├── expression:
            │   │           │   @ IntegerNode (location: (6...7))
            │   │           │   └── flags: decimal
            │   │           ├── keyword_loc: (8...14) = "rescue"
            │   │           └── rescue_expression:
            │   │               @ IntegerNode (location: (15...16))
            │   │               └── flags: decimal
            │   ├── closing_loc: ∅
            │   ├── block: ∅
            │   ├── flags: ∅
            │   └── name: "b"
            └── operator_loc: (2...3) = "="
