@ ProgramNode (location: (1,0)-(1,15))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,15))
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(1,15))
            ├── flags: ∅
            ├── receiver:
            │   @ CallNode (location: (1,0)-(1,3))
            │   ├── flags: variable_call, ignore_visibility
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── name: :foo
            │   ├── message_loc: (1,0)-(1,3) = "foo"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   └── block: ∅
            ├── call_operator_loc: ∅
            ├── name: :[]
            ├── message_loc: (1,3)-(1,15) = "[:baz => 1,]"
            ├── opening_loc: (1,3)-(1,4) = "["
            ├── arguments:
            │   @ ArgumentsNode (location: (1,4)-(1,13))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ KeywordHashNode (location: (1,4)-(1,13))
            │           ├── flags: symbol_keys
            │           └── elements: (length: 1)
            │               └── @ AssocNode (location: (1,4)-(1,13))
            │                   ├── key:
            │                   │   @ SymbolNode (location: (1,4)-(1,8))
            │                   │   ├── flags: forced_us_ascii_encoding
            │                   │   ├── opening_loc: (1,4)-(1,5) = ":"
            │                   │   ├── value_loc: (1,5)-(1,8) = "baz"
            │                   │   ├── closing_loc: ∅
            │                   │   └── unescaped: "baz"
            │                   ├── value:
            │                   │   @ IntegerNode (location: (1,12)-(1,13))
            │                   │   ├── flags: decimal
            │                   │   └── value: 1
            │                   └── operator_loc: (1,9)-(1,11) = "=>"
            ├── closing_loc: (1,14)-(1,15) = "]"
            └── block: ∅