@ ProgramNode (location: (1,0)-(1,6))
├── locals: [:a]
└── statements:
    @ StatementsNode (location: (1,0)-(1,6))
    └── body: (length: 1)
        └── @ LocalVariableWriteNode (location: (1,0)-(1,6))
            ├── name: :a
            ├── depth: 0
            ├── name_loc: (1,0)-(1,1) = "a"
            ├── value:
            │   @ IntegerNode (location: (1,4)-(1,6))
            │   ├── flags: decimal
            │   └── value: 42
            └── operator_loc: (1,2)-(1,3) = "="