@ ProgramNode (location: (1,0)-(4,1))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(4,1))
    └── body: (length: 3)
        ├── @ 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"
        ├── @ CallNode (location: (2,0)-(2,1))
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── message_loc: (2,0)-(2,1) = "b"
        │   ├── opening_loc: ∅
        │   ├── arguments: ∅
        │   ├── closing_loc: ∅
        │   ├── block: ∅
        │   ├── flags: variable_call
        │   └── name: "b"
        └── @ CallNode (location: (4,0)-(4,1))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (4,0)-(4,1) = "c"
            ├── opening_loc: ∅
            ├── arguments: ∅
            ├── closing_loc: ∅
            ├── block: ∅
            ├── flags: variable_call
            └── name: "c"