@ ProgramNode (location: (0...46))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...46))
    └── body: (length: 3)
        ├── @ LambdaNode (location: (0...12))
        │   ├── locals: []
        │   ├── operator_loc: (0...2) = "->"
        │   ├── opening_loc: (10...11) = "{"
        │   ├── closing_loc: (11...12) = "}"
        │   ├── parameters:
        │   │   @ BlockParametersNode (location: (2...9))
        │   │   ├── parameters:
        │   │   │   @ ParametersNode (location: (3...8))
        │   │   │   ├── requireds: (length: 0)
        │   │   │   ├── optionals: (length: 0)
        │   │   │   ├── rest: ∅
        │   │   │   ├── posts: (length: 0)
        │   │   │   ├── keywords: (length: 0)
        │   │   │   ├── keyword_rest:
        │   │   │   │   @ NoKeywordsParameterNode (location: (3...8))
        │   │   │   │   ├── operator_loc: (3...5) = "**"
        │   │   │   │   └── keyword_loc: (5...8) = "nil"
        │   │   │   └── block: ∅
        │   │   ├── locals: (length: 0)
        │   │   ├── opening_loc: (2...3) = "("
        │   │   └── closing_loc: (8...9) = ")"
        │   └── body: ∅
        ├── @ DefNode (location: (14...31))
        │   ├── name: :f
        │   ├── name_loc: (18...19) = "f"
        │   ├── receiver: ∅
        │   ├── parameters:
        │   │   @ ParametersNode (location: (20...25))
        │   │   ├── requireds: (length: 0)
        │   │   ├── optionals: (length: 0)
        │   │   ├── rest: ∅
        │   │   ├── posts: (length: 0)
        │   │   ├── keywords: (length: 0)
        │   │   ├── keyword_rest:
        │   │   │   @ NoKeywordsParameterNode (location: (20...25))
        │   │   │   ├── operator_loc: (20...22) = "**"
        │   │   │   └── keyword_loc: (22...25) = "nil"
        │   │   └── block: ∅
        │   ├── body: ∅
        │   ├── locals: []
        │   ├── def_keyword_loc: (14...17) = "def"
        │   ├── operator_loc: ∅
        │   ├── lparen_loc: (19...20) = "("
        │   ├── rparen_loc: (25...26) = ")"
        │   ├── equal_loc: ∅
        │   └── end_keyword_loc: (28...31) = "end"
        └── @ CallNode (location: (33...46))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (33...34) = "m"
            ├── opening_loc: ∅
            ├── arguments: ∅
            ├── closing_loc: ∅
            ├── block:
            │   @ BlockNode (location: (35...46))
            │   ├── locals: []
            │   ├── parameters:
            │   │   @ BlockParametersNode (location: (37...44))
            │   │   ├── parameters:
            │   │   │   @ ParametersNode (location: (38...43))
            │   │   │   ├── requireds: (length: 0)
            │   │   │   ├── optionals: (length: 0)
            │   │   │   ├── rest: ∅
            │   │   │   ├── posts: (length: 0)
            │   │   │   ├── keywords: (length: 0)
            │   │   │   ├── keyword_rest:
            │   │   │   │   @ NoKeywordsParameterNode (location: (38...43))
            │   │   │   │   ├── operator_loc: (38...40) = "**"
            │   │   │   │   └── keyword_loc: (40...43) = "nil"
            │   │   │   └── block: ∅
            │   │   ├── locals: (length: 0)
            │   │   ├── opening_loc: (37...38) = "|"
            │   │   └── closing_loc: (43...44) = "|"
            │   ├── body: ∅
            │   ├── opening_loc: (35...36) = "{"
            │   └── closing_loc: (45...46) = "}"
            ├── flags: ∅
            └── name: "m"
