@ ProgramNode (location: (1,0)-(1,16))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,16))
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(1,16))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (1,0)-(1,1) = "f"
            ├── opening_loc: (1,1)-(1,2) = "("
            ├── arguments:
            │   @ ArgumentsNode (location: (1,2)-(1,15))
            │   ├── arguments: (length: 2)
            │   │   ├── @ IntegerNode (location: (1,2)-(1,3))
            │   │   │   └── flags: decimal
            │   │   └── @ KeywordHashNode (location: (1,5)-(1,15))
            │   │       └── elements: (length: 2)
            │   │           ├── @ AssocNode (location: (1,5)-(1,10))
            │   │           │   ├── key:
            │   │           │   │   @ SymbolNode (location: (1,5)-(1,8))
            │   │           │   │   ├── opening_loc: ∅
            │   │           │   │   ├── value_loc: (1,5)-(1,7) = "kw"
            │   │           │   │   ├── closing_loc: (1,7)-(1,8) = ":"
            │   │           │   │   └── unescaped: "kw"
            │   │           │   ├── value:
            │   │           │   │   @ IntegerNode (location: (1,9)-(1,10))
            │   │           │   │   └── flags: decimal
            │   │           │   └── operator_loc: ∅
            │   │           └── @ AssocSplatNode (location: (1,12)-(1,15))
            │   │               ├── value:
            │   │               │   @ IntegerNode (location: (1,14)-(1,15))
            │   │               │   └── flags: decimal
            │   │               └── operator_loc: (1,12)-(1,14) = "**"
            │   └── flags: keyword_splat
            ├── closing_loc: (1,15)-(1,16) = ")"
            ├── block: ∅
            ├── flags: ∅
            └── name: :f
