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