@ ProgramNode (location: (1,0)-(3,19))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(3,19))
    └── body: (length: 2)
        ├── @ WhileNode (location: (1,0)-(1,21))
        │   ├── flags: ∅
        │   ├── keyword_loc: (1,0)-(1,5) = "while"
        │   ├── closing_loc: (1,18)-(1,21) = "end"
        │   ├── predicate:
        │   │   @ CallNode (location: (1,6)-(1,9))
        │   │   ├── flags: variable_call
        │   │   ├── receiver: ∅
        │   │   ├── call_operator_loc: ∅
        │   │   ├── name: :foo
        │   │   ├── message_loc: (1,6)-(1,9) = "foo"
        │   │   ├── opening_loc: ∅
        │   │   ├── arguments: ∅
        │   │   ├── closing_loc: ∅
        │   │   └── block: ∅
        │   └── statements:
        │       @ StatementsNode (location: (1,13)-(1,17))
        │       └── body: (length: 1)
        │           └── @ CallNode (location: (1,13)-(1,17))
        │               ├── flags: variable_call
        │               ├── receiver: ∅
        │               ├── call_operator_loc: ∅
        │               ├── name: :meth
        │               ├── message_loc: (1,13)-(1,17) = "meth"
        │               ├── opening_loc: ∅
        │               ├── arguments: ∅
        │               ├── closing_loc: ∅
        │               └── block: ∅
        └── @ WhileNode (location: (3,0)-(3,19))
            ├── flags: ∅
            ├── keyword_loc: (3,0)-(3,5) = "while"
            ├── closing_loc: (3,16)-(3,19) = "end"
            ├── predicate:
            │   @ CallNode (location: (3,6)-(3,9))
            │   ├── flags: variable_call
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── name: :foo
            │   ├── message_loc: (3,6)-(3,9) = "foo"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   └── block: ∅
            └── statements:
                @ StatementsNode (location: (3,11)-(3,15))
                └── body: (length: 1)
                    └── @ CallNode (location: (3,11)-(3,15))
                        ├── flags: variable_call
                        ├── receiver: ∅
                        ├── call_operator_loc: ∅
                        ├── name: :meth
                        ├── message_loc: (3,11)-(3,15) = "meth"
                        ├── opening_loc: ∅
                        ├── arguments: ∅
                        ├── closing_loc: ∅
                        └── block: ∅
