@ ProgramNode (location: (0...16))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...16))
    └── body: (length: 1)
        └── @ CallNode (location: (0...16))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (0...4) = "blah"
            ├── opening_loc: ∅
            ├── arguments: ∅
            ├── closing_loc: ∅
            ├── block:
            │   @ BlockNode (location: (5...16))
            │   ├── locals: [:k]
            │   ├── parameters:
            │   │   @ BlockParametersNode (location: (8...12))
            │   │   ├── parameters:
            │   │   │   @ ParametersNode (location: (9...11))
            │   │   │   ├── requireds: (length: 0)
            │   │   │   ├── optionals: (length: 0)
            │   │   │   ├── rest: ∅
            │   │   │   ├── posts: (length: 0)
            │   │   │   ├── keywords: (length: 1)
            │   │   │   │   └── @ KeywordParameterNode (location: (9...11))
            │   │   │   │       ├── name: :k
            │   │   │   │       ├── name_loc: (9...11) = "k:"
            │   │   │   │       └── value: ∅
            │   │   │   ├── keyword_rest: ∅
            │   │   │   └── block: ∅
            │   │   ├── locals: (length: 0)
            │   │   ├── opening_loc: (8...9) = "|"
            │   │   └── closing_loc: (11...12) = "|"
            │   ├── body: ∅
            │   ├── opening_loc: (5...7) = "do"
            │   └── closing_loc: (13...16) = "end"
            ├── flags: ∅
            └── name: "blah"
