@ ProgramNode (location: (1,0)-(3,3))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(3,3))
    └── body: (length: 1)
        └── @ BeginNode (location: (1,0)-(3,3))
            ├── begin_keyword_loc: (1,0)-(1,5) = "begin"
            ├── statements:
            │   @ StatementsNode (location: (2,2)-(2,5))
            │   └── body: (length: 1)
            │       └── @ CallNode (location: (2,2)-(2,5))
            │           ├── flags: variable_call
            │           ├── receiver: ∅
            │           ├── call_operator_loc: ∅
            │           ├── name: :foo
            │           ├── message_loc: (2,2)-(2,5) = "foo"
            │           ├── opening_loc: ∅
            │           ├── arguments: ∅
            │           ├── closing_loc: ∅
            │           └── block: ∅
            ├── rescue_clause: ∅
            ├── else_clause: ∅
            ├── ensure_clause: ∅
            └── end_keyword_loc: (3,0)-(3,3) = "end"
