@ ProgramNode (location: (0...21))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...21))
    └── body: (length: 2)
        ├── @ LambdaNode (location: (0...10))
        │   ├── locals: [:a]
        │   ├── operator_loc: (0...2) = "->"
        │   ├── opening_loc: (7...8) = "{"
        │   ├── closing_loc: (9...10) = "}"
        │   ├── parameters:
        │   │   @ BlockParametersNode (location: (3...6))
        │   │   ├── parameters:
        │   │   │   @ ParametersNode (location: (4...5))
        │   │   │   ├── requireds: (length: 1)
        │   │   │   │   └── @ RequiredParameterNode (location: (4...5))
        │   │   │   │       └── name: :a
        │   │   │   ├── optionals: (length: 0)
        │   │   │   ├── rest: ∅
        │   │   │   ├── posts: (length: 0)
        │   │   │   ├── keywords: (length: 0)
        │   │   │   ├── keyword_rest: ∅
        │   │   │   └── block: ∅
        │   │   ├── locals: (length: 0)
        │   │   ├── opening_loc: (3...4) = "("
        │   │   └── closing_loc: (5...6) = ")"
        │   └── body: ∅
        └── @ LambdaNode (location: (12...21))
            ├── locals: [:a]
            ├── operator_loc: (12...14) = "->"
            ├── opening_loc: (18...19) = "{"
            ├── closing_loc: (20...21) = "}"
            ├── parameters:
            │   @ BlockParametersNode (location: (14...17))
            │   ├── parameters:
            │   │   @ ParametersNode (location: (15...16))
            │   │   ├── requireds: (length: 1)
            │   │   │   └── @ RequiredParameterNode (location: (15...16))
            │   │   │       └── name: :a
            │   │   ├── optionals: (length: 0)
            │   │   ├── rest: ∅
            │   │   ├── posts: (length: 0)
            │   │   ├── keywords: (length: 0)
            │   │   ├── keyword_rest: ∅
            │   │   └── block: ∅
            │   ├── locals: (length: 0)
            │   ├── opening_loc: (14...15) = "("
            │   └── closing_loc: (16...17) = ")"
            └── body: ∅
