@ ProgramNode (location: (1,0)-(1,28))
├── locals: [:a, :b]
└── statements:
    @ StatementsNode (location: (1,0)-(1,28))
    └── body: (length: 1)
        └── @ ForNode (location: (1,0)-(1,28))
            ├── index:
            │   @ MultiTargetNode (location: (1,4)-(1,8))
            │   ├── lefts: (length: 2)
            │   │   ├── @ LocalVariableTargetNode (location: (1,4)-(1,5))
            │   │   │   ├── name: :a
            │   │   │   └── depth: 0
            │   │   └── @ LocalVariableTargetNode (location: (1,7)-(1,8))
            │   │       ├── name: :b
            │   │       └── depth: 0
            │   ├── rest: ∅
            │   ├── rights: (length: 0)
            │   ├── lparen_loc: ∅
            │   └── rparen_loc: ∅
            ├── collection:
            │   @ CallNode (location: (1,12)-(1,15))
            │   ├── flags: variable_call
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── name: :foo
            │   ├── message_loc: (1,12)-(1,15) = "foo"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   └── block: ∅
            ├── statements:
            │   @ StatementsNode (location: (1,17)-(1,23))
            │   └── body: (length: 1)
            │       └── @ CallNode (location: (1,17)-(1,23))
            │           ├── flags: ∅
            │           ├── receiver: ∅
            │           ├── call_operator_loc: ∅
            │           ├── name: :p
            │           ├── message_loc: (1,17)-(1,18) = "p"
            │           ├── opening_loc: ∅
            │           ├── arguments:
            │           │   @ ArgumentsNode (location: (1,19)-(1,23))
            │           │   ├── flags: ∅
            │           │   └── arguments: (length: 2)
            │           │       ├── @ LocalVariableReadNode (location: (1,19)-(1,20))
            │           │       │   ├── name: :a
            │           │       │   └── depth: 0
            │           │       └── @ LocalVariableReadNode (location: (1,22)-(1,23))
            │           │           ├── name: :b
            │           │           └── depth: 0
            │           ├── closing_loc: ∅
            │           └── block: ∅
            ├── for_keyword_loc: (1,0)-(1,3) = "for"
            ├── in_keyword_loc: (1,9)-(1,11) = "in"
            ├── do_keyword_loc: ∅
            └── end_keyword_loc: (1,25)-(1,28) = "end"
