@ ProgramNode (location: (1,0)-(1,11))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,11))
    └── body: (length: 1)
        └── @ IfNode (location: (1,0)-(1,11))
            ├── if_keyword_loc: ∅
            ├── predicate:
            │   @ CallNode (location: (1,0)-(1,3))
            │   ├── flags: variable_call
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── name: :foo
            │   ├── message_loc: (1,0)-(1,3) = "foo"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   └── block: ∅
            ├── then_keyword_loc: (1,4)-(1,5) = "?"
            ├── statements:
            │   @ StatementsNode (location: (1,6)-(1,7))
            │   └── body: (length: 1)
            │       └── @ IntegerNode (location: (1,6)-(1,7))
            │           └── flags: decimal
            ├── consequent:
            │   @ ElseNode (location: (1,8)-(1,11))
            │   ├── else_keyword_loc: (1,8)-(1,9) = ":"
            │   ├── statements:
            │   │   @ StatementsNode (location: (1,10)-(1,11))
            │   │   └── body: (length: 1)
            │   │       └── @ IntegerNode (location: (1,10)-(1,11))
            │   │           └── flags: decimal
            │   └── end_keyword_loc: ∅
            └── end_keyword_loc: ∅
