@ ProgramNode (location: (0...11))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...11))
    └── body: (length: 1)
        └── @ LambdaNode (location: (0...11))
            ├── locals: []
            ├── operator_loc: (0...2) = "->"
            ├── opening_loc: (5...7) = "do"
            ├── closing_loc: (8...11) = "end"
            ├── parameters:
            │   @ BlockParametersNode (location: (2...4))
            │   ├── parameters: ∅
            │   ├── locals: (length: 0)
            │   ├── opening_loc: (2...3) = "("
            │   └── closing_loc: (3...4) = ")"
            └── body: ∅
