@ ProgramNode (location: (0...16))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...16))
    └── body: (length: 1)
        └── @ CallNode (location: (0...16))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (0...1) = "a"
            ├── opening_loc: (1...2) = "("
            ├── arguments:
            │   @ ArgumentsNode (location: (2...15))
            │   └── arguments: (length: 1)
            │       └── @ ArrayNode (location: (2...15))
            │           ├── elements: (length: 2)
            │           │   ├── @ SymbolNode (location: (3...5))
            │           │   │   ├── opening_loc: (3...4) = ":"
            │           │   │   ├── value_loc: (4...5) = "b"
            │           │   │   ├── closing_loc: ∅
            │           │   │   └── unescaped: "b"
            │           │   └── @ KeywordHashNode (location: (7...14))
            │           │       └── elements: (length: 1)
            │           │           └── @ AssocNode (location: (7...14))
            │           │               ├── key:
            │           │               │   @ SymbolNode (location: (7...9))
            │           │               │   ├── opening_loc: (7...8) = ":"
            │           │               │   ├── value_loc: (8...9) = "c"
            │           │               │   ├── closing_loc: ∅
            │           │               │   └── unescaped: "c"
            │           │               ├── value:
            │           │               │   @ IntegerNode (location: (13...14))
            │           │               │   └── flags: decimal
            │           │               └── operator_loc: (10...12) = "=>"
            │           ├── opening_loc: (2...3) = "["
            │           └── closing_loc: (14...15) = "]"
            ├── closing_loc: (15...16) = ")"
            ├── block: ∅
            ├── flags: ∅
            └── name: "a"
