@ ProgramNode (location: (0...19))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...19))
    └── body: (length: 1)
        └── @ CallNode (location: (0...19))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (0...1) = "f"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (2...19))
            │   └── arguments: (length: 1)
            │       └── @ LambdaNode (location: (2...19))
            │           ├── locals: []
            │           ├── operator_loc: (2...4) = "->"
            │           ├── opening_loc: (7...8) = "{"
            │           ├── closing_loc: (18...19) = "}"
            │           ├── parameters:
            │           │   @ BlockParametersNode (location: (4...6))
            │           │   ├── parameters: ∅
            │           │   ├── locals: (length: 0)
            │           │   ├── opening_loc: (4...5) = "("
            │           │   └── closing_loc: (5...6) = ")"
            │           └── body:
            │               @ StatementsNode (location: (9...17))
            │               └── body: (length: 1)
            │                   └── @ CallNode (location: (9...17))
            │                       ├── receiver: ∅
            │                       ├── call_operator_loc: ∅
            │                       ├── message_loc: (9...10) = "g"
            │                       ├── opening_loc: ∅
            │                       ├── arguments: ∅
            │                       ├── closing_loc: ∅
            │                       ├── block:
            │                       │   @ BlockNode (location: (11...17))
            │                       │   ├── locals: []
            │                       │   ├── parameters: ∅
            │                       │   ├── body: ∅
            │                       │   ├── opening_loc: (11...13) = "do"
            │                       │   └── closing_loc: (14...17) = "end"
            │                       ├── flags: ∅
            │                       └── name: "g"
            ├── closing_loc: ∅
            ├── block: ∅
            ├── flags: ∅
            └── name: "f"
