@ ProgramNode (location: (0...56))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...56))
    └── body: (length: 3)
        ├── @ CallNode (location: (0...15))
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── message_loc: (0...6) = "assert"
        │   ├── opening_loc: ∅
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (7...15))
        │   │   └── arguments: (length: 1)
        │   │       └── @ KeywordHashNode (location: (7...15))
        │   │           └── elements: (length: 1)
        │   │               └── @ AssocNode (location: (7...15))
        │   │                   ├── key:
        │   │                   │   @ SymbolNode (location: (7...10))
        │   │                   │   ├── opening_loc: ∅
        │   │                   │   ├── value_loc: (7...9) = "do"
        │   │                   │   ├── closing_loc: (9...10) = ":"
        │   │                   │   └── unescaped: "do"
        │   │                   ├── value:
        │   │                   │   @ TrueNode (location: (11...15))
        │   │                   └── operator_loc: ∅
        │   ├── closing_loc: ∅
        │   ├── block: ∅
        │   ├── flags: ∅
        │   └── name: "assert"
        ├── @ CallNode (location: (17...28))
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── message_loc: (17...23) = "assert"
        │   ├── opening_loc: ∅
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (24...28))
        │   │   └── arguments: (length: 1)
        │   │       └── @ CallNode (location: (24...28))
        │   │           ├── receiver: ∅
        │   │           ├── call_operator_loc: ∅
        │   │           ├── message_loc: (24...28) = "dogs"
        │   │           ├── opening_loc: ∅
        │   │           ├── arguments: ∅
        │   │           ├── closing_loc: ∅
        │   │           ├── block: ∅
        │   │           ├── flags: variable_call
        │   │           └── name: "dogs"
        │   ├── closing_loc: ∅
        │   ├── block: ∅
        │   ├── flags: ∅
        │   └── name: "assert"
        └── @ CallNode (location: (30...56))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (30...31) = "f"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (32...56))
            │   └── arguments: (length: 1)
            │       └── @ KeywordHashNode (location: (32...56))
            │           └── elements: (length: 1)
            │               └── @ AssocNode (location: (32...56))
            │                   ├── key:
            │                   │   @ SymbolNode (location: (32...34))
            │                   │   ├── opening_loc: ∅
            │                   │   ├── value_loc: (32...33) = "x"
            │                   │   ├── closing_loc: (33...34) = ":"
            │                   │   └── unescaped: "x"
            │                   ├── value:
            │                   │   @ LambdaNode (location: (35...56))
            │                   │   ├── locals: []
            │                   │   ├── operator_loc: (35...37) = "->"
            │                   │   ├── opening_loc: (38...40) = "do"
            │                   │   ├── closing_loc: (53...56) = "end"
            │                   │   ├── parameters: ∅
            │                   │   └── body:
            │                   │       @ StatementsNode (location: (41...52))
            │                   │       └── body: (length: 1)
            │                   │           └── @ CallNode (location: (41...52))
            │                   │               ├── receiver: ∅
            │                   │               ├── call_operator_loc: ∅
            │                   │               ├── message_loc: (41...45) = "meth"
            │                   │               ├── opening_loc: ∅
            │                   │               ├── arguments: ∅
            │                   │               ├── closing_loc: ∅
            │                   │               ├── block:
            │                   │               │   @ BlockNode (location: (46...52))
            │                   │               │   ├── locals: []
            │                   │               │   ├── parameters: ∅
            │                   │               │   ├── body: ∅
            │                   │               │   ├── opening_loc: (46...48) = "do"
            │                   │               │   └── closing_loc: (49...52) = "end"
            │                   │               ├── flags: ∅
            │                   │               └── name: "meth"
            │                   └── operator_loc: ∅
            ├── closing_loc: ∅
            ├── block: ∅
            ├── flags: ∅
            └── name: "f"
