@ ProgramNode (location: (1,0)-(13,1))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(13,1))
    └── body: (length: 6)
        ├── @ CallNode (location: (1,0)-(2,1))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :lambda
        │   ├── message_loc: (1,0)-(1,6) = "lambda"
        │   ├── opening_loc: ∅
        │   ├── arguments: ∅
        │   ├── closing_loc: ∅
        │   └── block:
        │       @ BlockNode (location: (1,7)-(2,1))
        │       ├── locals: []
        │       ├── parameters: ∅
        │       ├── body: ∅
        │       ├── opening_loc: (1,7)-(1,8) = "{"
        │       └── closing_loc: (2,0)-(2,1) = "}"
        ├── @ CallNode (location: (3,0)-(5,1))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :lambda
        │   ├── message_loc: (3,0)-(3,6) = "lambda"
        │   ├── opening_loc: ∅
        │   ├── arguments: ∅
        │   ├── closing_loc: ∅
        │   └── block:
        │       @ BlockNode (location: (3,7)-(5,1))
        │       ├── locals: [:a, :b]
        │       ├── parameters:
        │       │   @ BlockParametersNode (location: (3,9)-(3,15))
        │       │   ├── parameters:
        │       │   │   @ ParametersNode (location: (3,10)-(3,14))
        │       │   │   ├── requireds: (length: 2)
        │       │   │   │   ├── @ RequiredParameterNode (location: (3,10)-(3,11))
        │       │   │   │   │   ├── flags: ∅
        │       │   │   │   │   └── name: :a
        │       │   │   │   └── @ RequiredParameterNode (location: (3,13)-(3,14))
        │       │   │   │       ├── flags: ∅
        │       │   │   │       └── name: :b
        │       │   │   ├── optionals: (length: 0)
        │       │   │   ├── rest: ∅
        │       │   │   ├── posts: (length: 0)
        │       │   │   ├── keywords: (length: 0)
        │       │   │   ├── keyword_rest: ∅
        │       │   │   └── block: ∅
        │       │   ├── locals: (length: 0)
        │       │   ├── opening_loc: (3,9)-(3,10) = "|"
        │       │   └── closing_loc: (3,14)-(3,15) = "|"
        │       ├── body:
        │       │   @ StatementsNode (location: (4,2)-(4,3))
        │       │   └── body: (length: 1)
        │       │       └── @ LocalVariableReadNode (location: (4,2)-(4,3))
        │       │           ├── name: :a
        │       │           └── depth: 0
        │       ├── opening_loc: (3,7)-(3,8) = "{"
        │       └── closing_loc: (5,0)-(5,1) = "}"
        ├── @ LambdaNode (location: (6,0)-(7,1))
        │   ├── locals: []
        │   ├── operator_loc: (6,0)-(6,2) = "->"
        │   ├── opening_loc: (6,5)-(6,6) = "{"
        │   ├── closing_loc: (7,0)-(7,1) = "}"
        │   ├── parameters:
        │   │   @ BlockParametersNode (location: (6,2)-(6,4))
        │   │   ├── parameters: ∅
        │   │   ├── locals: (length: 0)
        │   │   ├── opening_loc: (6,2)-(6,3) = "("
        │   │   └── closing_loc: (6,3)-(6,4) = ")"
        │   └── body: ∅
        ├── @ LambdaNode (location: (8,0)-(9,1))
        │   ├── locals: [:a]
        │   ├── operator_loc: (8,0)-(8,2) = "->"
        │   ├── opening_loc: (8,6)-(8,7) = "{"
        │   ├── closing_loc: (9,0)-(9,1) = "}"
        │   ├── parameters:
        │   │   @ BlockParametersNode (location: (8,2)-(8,5))
        │   │   ├── parameters:
        │   │   │   @ ParametersNode (location: (8,3)-(8,4))
        │   │   │   ├── requireds: (length: 1)
        │   │   │   │   └── @ RequiredParameterNode (location: (8,3)-(8,4))
        │   │   │   │       ├── flags: ∅
        │   │   │   │       └── name: :a
        │   │   │   ├── optionals: (length: 0)
        │   │   │   ├── rest: ∅
        │   │   │   ├── posts: (length: 0)
        │   │   │   ├── keywords: (length: 0)
        │   │   │   ├── keyword_rest: ∅
        │   │   │   └── block: ∅
        │   │   ├── locals: (length: 0)
        │   │   ├── opening_loc: (8,2)-(8,3) = "("
        │   │   └── closing_loc: (8,4)-(8,5) = ")"
        │   └── body: ∅
        ├── @ LambdaNode (location: (10,0)-(11,1))
        │   ├── locals: [:a, :b]
        │   ├── operator_loc: (10,0)-(10,2) = "->"
        │   ├── opening_loc: (10,9)-(10,10) = "{"
        │   ├── closing_loc: (11,0)-(11,1) = "}"
        │   ├── parameters:
        │   │   @ BlockParametersNode (location: (10,2)-(10,8))
        │   │   ├── parameters:
        │   │   │   @ ParametersNode (location: (10,3)-(10,7))
        │   │   │   ├── requireds: (length: 2)
        │   │   │   │   ├── @ RequiredParameterNode (location: (10,3)-(10,4))
        │   │   │   │   │   ├── flags: ∅
        │   │   │   │   │   └── name: :a
        │   │   │   │   └── @ RequiredParameterNode (location: (10,6)-(10,7))
        │   │   │   │       ├── flags: ∅
        │   │   │   │       └── name: :b
        │   │   │   ├── optionals: (length: 0)
        │   │   │   ├── rest: ∅
        │   │   │   ├── posts: (length: 0)
        │   │   │   ├── keywords: (length: 0)
        │   │   │   ├── keyword_rest: ∅
        │   │   │   └── block: ∅
        │   │   ├── locals: (length: 0)
        │   │   ├── opening_loc: (10,2)-(10,3) = "("
        │   │   └── closing_loc: (10,7)-(10,8) = ")"
        │   └── body: ∅
        └── @ LambdaNode (location: (12,0)-(13,1))
            ├── locals: [:a, :b, :c]
            ├── operator_loc: (12,0)-(12,2) = "->"
            ├── opening_loc: (12,12)-(12,13) = "{"
            ├── closing_loc: (13,0)-(13,1) = "}"
            ├── parameters:
            │   @ BlockParametersNode (location: (12,2)-(12,11))
            │   ├── parameters:
            │   │   @ ParametersNode (location: (12,3)-(12,7))
            │   │   ├── requireds: (length: 2)
            │   │   │   ├── @ RequiredParameterNode (location: (12,3)-(12,4))
            │   │   │   │   ├── flags: ∅
            │   │   │   │   └── name: :a
            │   │   │   └── @ RequiredParameterNode (location: (12,6)-(12,7))
            │   │   │       ├── flags: ∅
            │   │   │       └── name: :b
            │   │   ├── optionals: (length: 0)
            │   │   ├── rest: ∅
            │   │   ├── posts: (length: 0)
            │   │   ├── keywords: (length: 0)
            │   │   ├── keyword_rest: ∅
            │   │   └── block: ∅
            │   ├── locals: (length: 1)
            │   │   └── @ BlockLocalVariableNode (location: (12,9)-(12,10))
            │   │       ├── flags: ∅
            │   │       └── name: :c
            │   ├── opening_loc: (12,2)-(12,3) = "("
            │   └── closing_loc: (12,10)-(12,11) = ")"
            └── body: ∅