@ ProgramNode (location: (1,0)-(1,9))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,9))
    └── body: (length: 1)
        └── @ InstanceVariableWriteNode (location: (1,0)-(1,9))
            ├── name: :@var
            ├── name_loc: (1,0)-(1,4) = "@var"
            ├── value:
            │   @ IntegerNode (location: (1,7)-(1,9))
            │   └── flags: decimal
            └── operator_loc: (1,5)-(1,6) = "="
