@ ProgramNode (location: (1,0)-(1,9))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,9))
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(1,9))
            ├── receiver:
            │   @ 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
            ├── call_operator_loc: (1,1)-(1,2) = "."
            ├── message_loc: (1,2)-(1,3) = "b"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (1,4)-(1,9))
            │   ├── arguments: (length: 1)
            │   │   └── @ CallNode (location: (1,4)-(1,9))
            │   │       ├── receiver:
            │   │       │   @ CallNode (location: (1,4)-(1,5))
            │   │       │   ├── receiver: ∅
            │   │       │   ├── call_operator_loc: ∅
            │   │       │   ├── message_loc: (1,4)-(1,5) = "c"
            │   │       │   ├── opening_loc: ∅
            │   │       │   ├── arguments: ∅
            │   │       │   ├── closing_loc: ∅
            │   │       │   ├── block: ∅
            │   │       │   ├── flags: variable_call
            │   │       │   └── name: :c
            │   │       ├── call_operator_loc: (1,5)-(1,6) = "."
            │   │       ├── message_loc: (1,6)-(1,7) = "d"
            │   │       ├── opening_loc: ∅
            │   │       ├── arguments:
            │   │       │   @ ArgumentsNode (location: (1,8)-(1,9))
            │   │       │   ├── arguments: (length: 1)
            │   │       │   │   └── @ IntegerNode (location: (1,8)-(1,9))
            │   │       │   │       └── flags: decimal
            │   │       │   └── flags: ∅
            │   │       ├── closing_loc: ∅
            │   │       ├── block: ∅
            │   │       ├── flags: ∅
            │   │       └── name: :d
            │   └── flags: ∅
            ├── closing_loc: ∅
            ├── block: ∅
            ├── flags: ∅
            └── name: :b
