@ ProgramNode (location: (1,0)-(2,12))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(2,12))
    └── body: (length: 1)
        └── @ IfNode (location: (1,0)-(2,12))
            ├── if_keyword_loc: (1,0)-(1,2) = "if"
            ├── predicate:
            │   @ CallNode (location: (1,3)-(1,6))
            │   ├── flags: variable_call, ignore_visibility
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── name: :foo
            │   ├── message_loc: (1,3)-(1,6) = "foo"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   └── block: ∅
            ├── then_keyword_loc: (2,0)-(2,4) = "then"
            ├── statements:
            │   @ StatementsNode (location: (2,5)-(2,8))
            │   └── body: (length: 1)
            │       └── @ CallNode (location: (2,5)-(2,8))
            │           ├── flags: variable_call, ignore_visibility
            │           ├── receiver: ∅
            │           ├── call_operator_loc: ∅
            │           ├── name: :bar
            │           ├── message_loc: (2,5)-(2,8) = "bar"
            │           ├── opening_loc: ∅
            │           ├── arguments: ∅
            │           ├── closing_loc: ∅
            │           └── block: ∅
            ├── consequent: ∅
            └── end_keyword_loc: (2,9)-(2,12) = "end"