@ ProgramNode (location: (0...17))
├── locals: [:a]
└── statements:
    @ StatementsNode (location: (0...17))
    └── body: (length: 1)
        └── @ LocalVariableWriteNode (location: (0...17))
            ├── name: :a
            ├── depth: 0
            ├── name_loc: (0...1) = "a"
            ├── value:
            │   @ IfNode (location: (2...17))
            │   ├── if_keyword_loc: ∅
            │   ├── predicate:
            │   │   @ CallNode (location: (2...3))
            │   │   ├── receiver: ∅
            │   │   ├── call_operator_loc: ∅
            │   │   ├── message_loc: (2...3) = "b"
            │   │   ├── opening_loc: ∅
            │   │   ├── arguments: ∅
            │   │   ├── closing_loc: ∅
            │   │   ├── block: ∅
            │   │   ├── flags: variable_call
            │   │   └── name: "b"
            │   ├── statements:
            │   │   @ StatementsNode (location: (6...10))
            │   │   └── body: (length: 1)
            │   │       └── @ TrueNode (location: (6...10))
            │   ├── consequent:
            │   │   @ ElseNode (location: (10...17))
            │   │   ├── else_keyword_loc: (10...11) = ":"
            │   │   ├── statements:
            │   │   │   @ StatementsNode (location: (12...17))
            │   │   │   └── body: (length: 1)
            │   │   │       └── @ FalseNode (location: (12...17))
            │   │   └── end_keyword_loc: ∅
            │   └── end_keyword_loc: ∅
            └── operator_loc: (1...2) = "="
