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