@ ProgramNode (location: (0...43))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...43))
    └── body: (length: 1)
        └── @ DefNode (location: (0...43))
            ├── name: :foo
            ├── name_loc: (4...7) = "foo"
            ├── receiver: ∅
            ├── parameters:
            │   @ ParametersNode (location: (8...19))
            │   ├── requireds: (length: 1)
            │   │   └── @ RequiredParameterNode (location: (8...16))
            │   │       └── name: :argument
            │   ├── optionals: (length: 0)
            │   ├── rest:
            │   │   @ RestParameterNode (location: (18...19))
            │   │   ├── name: nil
            │   │   ├── name_loc: ∅
            │   │   └── operator_loc: (18...19) = "*"
            │   ├── posts: (length: 0)
            │   ├── keywords: (length: 0)
            │   ├── keyword_rest: ∅
            │   └── block: ∅
            ├── body:
            │   @ StatementsNode (location: (22...38))
            │   └── body: (length: 1)
            │       └── @ CallNode (location: (22...38))
            │           ├── receiver: ∅
            │           ├── call_operator_loc: ∅
            │           ├── message_loc: (22...25) = "bar"
            │           ├── opening_loc: (25...26) = "("
            │           ├── arguments:
            │           │   @ ArgumentsNode (location: (26...37))
            │           │   └── arguments: (length: 2)
            │           │       ├── @ LocalVariableReadNode (location: (26...34))
            │           │       │   ├── name: :argument
            │           │       │   └── depth: 0
            │           │       └── @ SplatNode (location: (36...37))
            │           │           ├── operator_loc: (36...37) = "*"
            │           │           └── expression: ∅
            │           ├── closing_loc: (37...38) = ")"
            │           ├── block: ∅
            │           ├── flags: ∅
            │           └── name: "bar"
            ├── locals: [:argument, :*]
            ├── def_keyword_loc: (0...3) = "def"
            ├── operator_loc: ∅
            ├── lparen_loc: (7...8) = "("
            ├── rparen_loc: (19...20) = ")"
            ├── equal_loc: ∅
            └── end_keyword_loc: (40...43) = "end"
