@ ProgramNode (location: (1,0)-(1,4))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,4))
    └── body: (length: 1)
        └── @ RangeNode (location: (1,0)-(1,4))
            ├── left:
            │   @ CallNode (location: (1,0)-(1,1))
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── message_loc: (1,0)-(1,1) = "a"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   ├── block: ∅
            │   ├── flags: variable_call
            │   └── name: "a"
            ├── right: ∅
            ├── operator_loc: (1,1)-(1,4) = "..."
            └── flags: exclude_end