@ ProgramNode (location: (1,0)-(3,27))
├── locals: [:a, :b]
└── statements:
    @ StatementsNode (location: (1,0)-(3,27))
    └── body: (length: 3)
        ├── @ DefinedNode (location: (1,0)-(1,14))
        │   ├── lparen_loc: (1,8)-(1,9) = "("
        │   ├── value:
        │   │   @ InstanceVariableReadNode (location: (1,9)-(1,13))
        │   │   └── name: :@foo
        │   ├── rparen_loc: (1,13)-(1,14) = ")"
        │   └── keyword_loc: (1,0)-(1,8) = "defined?"
        ├── @ DefinedNode (location: (2,0)-(2,13))
        │   ├── lparen_loc: (2,8)-(2,9) = "("
        │   ├── value:
        │   │   @ ConstantReadNode (location: (2,9)-(2,12))
        │   │   └── name: :Foo
        │   ├── rparen_loc: (2,12)-(2,13) = ")"
        │   └── keyword_loc: (2,0)-(2,8) = "defined?"
        └── @ DefinedNode (location: (3,0)-(3,27))
            ├── lparen_loc: (3,8)-(3,9) = "("
            ├── value:
            │   @ ParenthesesNode (location: (3,9)-(3,26))
            │   ├── body:
            │   │   @ StatementsNode (location: (3,10)-(3,25))
            │   │   └── body: (length: 1)
            │   │       └── @ MultiWriteNode (location: (3,10)-(3,25))
            │   │           ├── lefts: (length: 2)
            │   │           │   ├── @ LocalVariableTargetNode (location: (3,11)-(3,12))
            │   │           │   │   ├── name: :a
            │   │           │   │   └── depth: 0
            │   │           │   └── @ LocalVariableTargetNode (location: (3,14)-(3,15))
            │   │           │       ├── name: :b
            │   │           │       └── depth: 0
            │   │           ├── rest: ∅
            │   │           ├── rights: (length: 0)
            │   │           ├── lparen_loc: (3,10)-(3,11) = "("
            │   │           ├── rparen_loc: (3,15)-(3,16) = ")"
            │   │           ├── operator_loc: (3,17)-(3,18) = "="
            │   │           └── value:
            │   │               @ ArrayNode (location: (3,19)-(3,25))
            │   │               ├── flags: ∅
            │   │               ├── elements: (length: 2)
            │   │               │   ├── @ IntegerNode (location: (3,20)-(3,21))
            │   │               │   │   ├── flags: decimal
            │   │               │   │   └── value: 1
            │   │               │   └── @ IntegerNode (location: (3,23)-(3,24))
            │   │               │       ├── flags: decimal
            │   │               │       └── value: 2
            │   │               ├── opening_loc: (3,19)-(3,20) = "["
            │   │               └── closing_loc: (3,24)-(3,25) = "]"
            │   ├── opening_loc: (3,9)-(3,10) = "("
            │   └── closing_loc: (3,25)-(3,26) = ")"
            ├── rparen_loc: (3,26)-(3,27) = ")"
            └── keyword_loc: (3,0)-(3,8) = "defined?"