@ ProgramNode (location: (0...18))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...18))
    └── body: (length: 1)
        └── @ CallNode (location: (0...18))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (0...1) = "a"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (2...11))
            │   └── arguments: (length: 1)
            │       └── @ ArrayNode (location: (2...11))
            │           ├── elements: (length: 1)
            │           │   └── @ LambdaNode (location: (3...10))
            │           │       ├── locals: []
            │           │       ├── operator_loc: (3...5) = "->"
            │           │       ├── opening_loc: (8...9) = "{"
            │           │       ├── closing_loc: (9...10) = "}"
            │           │       ├── parameters:
            │           │       │   @ BlockParametersNode (location: (5...7))
            │           │       │   ├── parameters: ∅
            │           │       │   ├── locals: (length: 0)
            │           │       │   ├── opening_loc: (5...6) = "("
            │           │       │   └── closing_loc: (6...7) = ")"
            │           │       └── body: ∅
            │           ├── opening_loc: (2...3) = "["
            │           └── closing_loc: (10...11) = "]"
            ├── closing_loc: ∅
            ├── block:
            │   @ BlockNode (location: (12...18))
            │   ├── locals: []
            │   ├── parameters: ∅
            │   ├── body: ∅
            │   ├── opening_loc: (12...14) = "do"
            │   └── closing_loc: (15...18) = "end"
            ├── flags: ∅
            └── name: "a"
