@ ProgramNode (location: (0...25))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...25))
    └── body: (length: 1)
        └── @ CallNode (location: (0...25))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (0...1) = "x"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (2...25))
            │   └── arguments: (length: 1)
            │       └── @ LambdaNode (location: (2...25))
            │           ├── locals: []
            │           ├── operator_loc: (2...4) = "->"
            │           ├── opening_loc: (8...10) = "do"
            │           ├── closing_loc: (22...25) = "end"
            │           ├── parameters:
            │           │   @ BlockParametersNode (location: (5...7))
            │           │   ├── parameters: ∅
            │           │   ├── locals: (length: 0)
            │           │   ├── opening_loc: (5...6) = "("
            │           │   └── closing_loc: (6...7) = ")"
            │           └── body:
            │               @ StatementsNode (location: (11...21))
            │               └── body: (length: 1)
            │                   └── @ CallNode (location: (11...21))
            │                       ├── receiver:
            │                       │   @ CallNode (location: (11...12))
            │                       │   ├── receiver: ∅
            │                       │   ├── call_operator_loc: ∅
            │                       │   ├── message_loc: (11...12) = "a"
            │                       │   ├── opening_loc: ∅
            │                       │   ├── arguments: ∅
            │                       │   ├── closing_loc: ∅
            │                       │   ├── block: ∅
            │                       │   ├── flags: variable_call
            │                       │   └── name: "a"
            │                       ├── call_operator_loc: (12...13) = "."
            │                       ├── message_loc: (13...14) = "b"
            │                       ├── opening_loc: ∅
            │                       ├── arguments: ∅
            │                       ├── closing_loc: ∅
            │                       ├── block:
            │                       │   @ BlockNode (location: (15...21))
            │                       │   ├── locals: []
            │                       │   ├── parameters: ∅
            │                       │   ├── body: ∅
            │                       │   ├── opening_loc: (15...17) = "do"
            │                       │   └── closing_loc: (18...21) = "end"
            │                       ├── flags: ∅
            │                       └── name: "b"
            ├── closing_loc: ∅
            ├── block: ∅
            ├── flags: ∅
            └── name: "x"
