@ ProgramNode (location: (1,0)-(7,9))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(7,9))
    └── body: (length: 4)
        ├── @ CallNode (location: (1,0)-(1,11))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :f
        │   ├── message_loc: (1,0)-(1,1) = "f"
        │   ├── opening_loc: ∅
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (1,2)-(1,11))
        │   │   ├── flags: ∅
        │   │   └── arguments: (length: 1)
        │   │       └── @ LambdaNode (location: (1,2)-(1,11))
        │   │           ├── locals: []
        │   │           ├── operator_loc: (1,2)-(1,4) = "->"
        │   │           ├── opening_loc: (1,5)-(1,7) = "do"
        │   │           ├── closing_loc: (1,8)-(1,11) = "end"
        │   │           ├── parameters: ∅
        │   │           └── body: ∅
        │   ├── closing_loc: ∅
        │   └── block: ∅
        ├── @ CallNode (location: (3,0)-(3,7))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :f
        │   ├── message_loc: (3,0)-(3,1) = "f"
        │   ├── opening_loc: ∅
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (3,2)-(3,7))
        │   │   ├── flags: ∅
        │   │   └── arguments: (length: 1)
        │   │       └── @ LambdaNode (location: (3,2)-(3,7))
        │   │           ├── locals: []
        │   │           ├── operator_loc: (3,2)-(3,4) = "->"
        │   │           ├── opening_loc: (3,5)-(3,6) = "{"
        │   │           ├── closing_loc: (3,6)-(3,7) = "}"
        │   │           ├── parameters: ∅
        │   │           └── body: ∅
        │   ├── closing_loc: ∅
        │   └── block: ∅
        ├── @ CallNode (location: (5,0)-(5,13))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :f
        │   ├── message_loc: (5,0)-(5,1) = "f"
        │   ├── opening_loc: ∅
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (5,2)-(5,13))
        │   │   ├── flags: ∅
        │   │   └── arguments: (length: 1)
        │   │       └── @ LambdaNode (location: (5,2)-(5,13))
        │   │           ├── locals: []
        │   │           ├── operator_loc: (5,2)-(5,4) = "->"
        │   │           ├── opening_loc: (5,7)-(5,9) = "do"
        │   │           ├── closing_loc: (5,10)-(5,13) = "end"
        │   │           ├── parameters:
        │   │           │   @ BlockParametersNode (location: (5,4)-(5,6))
        │   │           │   ├── parameters: ∅
        │   │           │   ├── locals: (length: 0)
        │   │           │   ├── opening_loc: (5,4)-(5,5) = "("
        │   │           │   └── closing_loc: (5,5)-(5,6) = ")"
        │   │           └── body: ∅
        │   ├── closing_loc: ∅
        │   └── block: ∅
        └── @ CallNode (location: (7,0)-(7,9))
            ├── flags: ignore_visibility
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── name: :f
            ├── message_loc: (7,0)-(7,1) = "f"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (7,2)-(7,9))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ LambdaNode (location: (7,2)-(7,9))
            │           ├── locals: []
            │           ├── operator_loc: (7,2)-(7,4) = "->"
            │           ├── opening_loc: (7,7)-(7,8) = "{"
            │           ├── closing_loc: (7,8)-(7,9) = "}"
            │           ├── parameters:
            │           │   @ BlockParametersNode (location: (7,4)-(7,6))
            │           │   ├── parameters: ∅
            │           │   ├── locals: (length: 0)
            │           │   ├── opening_loc: (7,4)-(7,5) = "("
            │           │   └── closing_loc: (7,5)-(7,6) = ")"
            │           └── body: ∅
            ├── closing_loc: ∅
            └── block: ∅