@ ProgramNode (location: (1,0)-(1,14))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,14))
    └── body: (length: 1)
        └── @ WhileNode (location: (1,0)-(1,14))
            ├── flags: ∅
            ├── keyword_loc: (1,5)-(1,10) = "while"
            ├── closing_loc: ∅
            ├── predicate:
            │   @ CallNode (location: (1,11)-(1,14))
            │   ├── flags: variable_call
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── name: :foo
            │   ├── message_loc: (1,11)-(1,14) = "foo"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   └── block: ∅
            └── statements:
                @ StatementsNode (location: (1,0)-(1,4))
                └── body: (length: 1)
                    └── @ CallNode (location: (1,0)-(1,4))
                        ├── flags: variable_call
                        ├── receiver: ∅
                        ├── call_operator_loc: ∅
                        ├── name: :meth
                        ├── message_loc: (1,0)-(1,4) = "meth"
                        ├── opening_loc: ∅
                        ├── arguments: ∅
                        ├── closing_loc: ∅
                        └── block: ∅
