@ ProgramNode (location: (1,0)-(1,20))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,20))
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(1,20))
            ├── receiver:
            │   @ CallNode (location: (1,0)-(1,3))
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── message_loc: (1,0)-(1,3) = "foo"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   ├── block: ∅
            │   ├── flags: variable_call
            │   └── name: :foo
            ├── call_operator_loc: ∅
            ├── message_loc: (1,3)-(1,20) = "[bar, :baz => 1,]"
            ├── opening_loc: (1,3)-(1,4) = "["
            ├── arguments:
            │   @ ArgumentsNode (location: (1,4)-(1,18))
            │   ├── arguments: (length: 2)
            │   │   ├── @ CallNode (location: (1,4)-(1,7))
            │   │   │   ├── receiver: ∅
            │   │   │   ├── call_operator_loc: ∅
            │   │   │   ├── message_loc: (1,4)-(1,7) = "bar"
            │   │   │   ├── opening_loc: ∅
            │   │   │   ├── arguments: ∅
            │   │   │   ├── closing_loc: ∅
            │   │   │   ├── block: ∅
            │   │   │   ├── flags: variable_call
            │   │   │   └── name: :bar
            │   │   └── @ KeywordHashNode (location: (1,9)-(1,18))
            │   │       └── elements: (length: 1)
            │   │           └── @ AssocNode (location: (1,9)-(1,18))
            │   │               ├── key:
            │   │               │   @ SymbolNode (location: (1,9)-(1,13))
            │   │               │   ├── opening_loc: (1,9)-(1,10) = ":"
            │   │               │   ├── value_loc: (1,10)-(1,13) = "baz"
            │   │               │   ├── closing_loc: ∅
            │   │               │   └── unescaped: "baz"
            │   │               ├── value:
            │   │               │   @ IntegerNode (location: (1,17)-(1,18))
            │   │               │   └── flags: decimal
            │   │               └── operator_loc: (1,14)-(1,16) = "=>"
            │   └── flags: ∅
            ├── closing_loc: (1,19)-(1,20) = "]"
            ├── block: ∅
            ├── flags: ∅
            └── name: :[]
