@ ProgramNode (location: (1,0)-(1,19))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,19))
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(1,19))
            ├── flags: ignore_visibility
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── name: :foo
            ├── message_loc: (1,0)-(1,3) = "foo"
            ├── opening_loc: (1,3)-(1,4) = "("
            ├── arguments:
            │   @ ArgumentsNode (location: (1,4)-(1,18))
            │   ├── flags: ∅
            │   └── arguments: (length: 2)
            │       ├── @ SymbolNode (location: (1,4)-(1,8))
            │       │   ├── flags: forced_us_ascii_encoding
            │       │   ├── opening_loc: (1,4)-(1,5) = ":"
            │       │   ├── value_loc: (1,5)-(1,8) = "bar"
            │       │   ├── closing_loc: ∅
            │       │   └── unescaped: "bar"
            │       └── @ KeywordHashNode (location: (1,10)-(1,18))
            │           ├── flags: symbol_keys
            │           └── elements: (length: 1)
            │               └── @ AssocNode (location: (1,10)-(1,18))
            │                   ├── key:
            │                   │   @ SymbolNode (location: (1,10)-(1,14))
            │                   │   ├── flags: forced_us_ascii_encoding
            │                   │   ├── opening_loc: ∅
            │                   │   ├── value_loc: (1,10)-(1,13) = "baz"
            │                   │   ├── closing_loc: (1,13)-(1,14) = ":"
            │                   │   └── unescaped: "baz"
            │                   ├── value:
            │                   │   @ NilNode (location: (1,15)-(1,18))
            │                   └── operator_loc: ∅
            ├── closing_loc: (1,18)-(1,19) = ")"
            └── block: ∅
