@ ProgramNode (location: (1,0)-(3,7))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(3,7))
    └── body: (length: 2)
        ├── @ CallNode (location: (1,0)-(1,6))
        │   ├── flags: ∅
        │   ├── receiver:
        │   │   @ CallNode (location: (1,0)-(1,1))
        │   │   ├── flags: variable_call, ignore_visibility
        │   │   ├── receiver: ∅
        │   │   ├── call_operator_loc: ∅
        │   │   ├── name: :f
        │   │   ├── message_loc: (1,0)-(1,1) = "f"
        │   │   ├── opening_loc: ∅
        │   │   ├── arguments: ∅
        │   │   ├── closing_loc: ∅
        │   │   └── block: ∅
        │   ├── call_operator_loc: (1,1)-(1,2) = "."
        │   ├── name: :call
        │   ├── message_loc: ∅
        │   ├── opening_loc: (1,2)-(1,3) = "("
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (1,3)-(1,5))
        │   │   ├── flags: ∅
        │   │   └── arguments: (length: 1)
        │   │       └── @ IntegerNode (location: (1,3)-(1,5))
        │   │           ├── flags: decimal
        │   │           └── value: 42
        │   ├── closing_loc: (1,5)-(1,6) = ")"
        │   └── block: ∅
        └── @ CallNode (location: (3,0)-(3,7))
            ├── flags: ∅
            ├── receiver:
            │   @ CallNode (location: (3,0)-(3,1))
            │   ├── flags: variable_call, ignore_visibility
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── name: :f
            │   ├── message_loc: (3,0)-(3,1) = "f"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   └── block: ∅
            ├── call_operator_loc: (3,1)-(3,3) = "::"
            ├── name: :call
            ├── message_loc: ∅
            ├── opening_loc: (3,3)-(3,4) = "("
            ├── arguments:
            │   @ ArgumentsNode (location: (3,4)-(3,6))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ IntegerNode (location: (3,4)-(3,6))
            │           ├── flags: decimal
            │           └── value: 42
            ├── closing_loc: (3,6)-(3,7) = ")"
            └── block: ∅