@ ProgramNode (location: (1,0)-(1,5))
├── flags: ∅
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,5))
    ├── flags: ∅
    └── body: (length: 1)
        └── @ ClassVariableReadNode (location: (1,0)-(1,5))
            ├── flags: newline
            └── name: :@@foo
