@ ProgramNode (location: (1,0)-(1,33))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,33))
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(1,33))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (1,0)-(1,3) = "bar"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (1,4)-(1,33))
            │   ├── arguments: (length: 1)
            │   │   └── @ DefNode (location: (1,4)-(1,33))
            │   │       ├── name: :foo
            │   │       ├── name_loc: (1,8)-(1,11) = "foo"
            │   │       ├── receiver: ∅
            │   │       ├── parameters: ∅
            │   │       ├── body:
            │   │       │   @ StatementsNode (location: (1,13)-(1,29))
            │   │       │   └── body: (length: 1)
            │   │       │       └── @ CallNode (location: (1,13)-(1,29))
            │   │       │           ├── receiver:
            │   │       │           │   @ SelfNode (location: (1,13)-(1,17))
            │   │       │           ├── call_operator_loc: (1,17)-(1,18) = "."
            │   │       │           ├── message_loc: (1,18)-(1,22) = "each"
            │   │       │           ├── opening_loc: ∅
            │   │       │           ├── arguments: ∅
            │   │       │           ├── closing_loc: ∅
            │   │       │           ├── block:
            │   │       │           │   @ BlockNode (location: (1,23)-(1,29))
            │   │       │           │   ├── locals: []
            │   │       │           │   ├── parameters: ∅
            │   │       │           │   ├── body: ∅
            │   │       │           │   ├── opening_loc: (1,23)-(1,25) = "do"
            │   │       │           │   └── closing_loc: (1,26)-(1,29) = "end"
            │   │       │           ├── flags: ∅
            │   │       │           └── name: :each
            │   │       ├── locals: []
            │   │       ├── def_keyword_loc: (1,4)-(1,7) = "def"
            │   │       ├── operator_loc: ∅
            │   │       ├── lparen_loc: ∅
            │   │       ├── rparen_loc: ∅
            │   │       ├── equal_loc: ∅
            │   │       └── end_keyword_loc: (1,30)-(1,33) = "end"
            │   └── flags: ∅
            ├── closing_loc: ∅
            ├── block: ∅
            ├── flags: ∅
            └── name: :bar
