@ ProgramNode (location: (1,0)-(1,24))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,24))
    └── body: (length: 1)
        └── @ WhileNode (location: (1,0)-(1,24))
            ├── keyword_loc: (1,15)-(1,20) = "while"
            ├── closing_loc: ∅
            ├── predicate:
            │   @ CallNode (location: (1,21)-(1,24))
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── message_loc: (1,21)-(1,24) = "foo"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   ├── block: ∅
            │   ├── flags: variable_call
            │   └── name: :foo
            ├── statements:
            │   @ StatementsNode (location: (1,0)-(1,14))
            │   └── body: (length: 1)
            │       └── @ BeginNode (location: (1,0)-(1,14))
            │           ├── begin_keyword_loc: (1,0)-(1,5) = "begin"
            │           ├── statements:
            │           │   @ StatementsNode (location: (1,6)-(1,10))
            │           │   └── body: (length: 1)
            │           │       └── @ CallNode (location: (1,6)-(1,10))
            │           │           ├── receiver: ∅
            │           │           ├── call_operator_loc: ∅
            │           │           ├── message_loc: (1,6)-(1,10) = "meth"
            │           │           ├── opening_loc: ∅
            │           │           ├── arguments: ∅
            │           │           ├── closing_loc: ∅
            │           │           ├── block: ∅
            │           │           ├── flags: variable_call
            │           │           └── name: :meth
            │           ├── rescue_clause: ∅
            │           ├── else_clause: ∅
            │           ├── ensure_clause: ∅
            │           └── end_keyword_loc: (1,11)-(1,14) = "end"
            └── flags: begin_modifier
