@ ProgramNode (location: (1,0)-(1,12))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,12))
    └── body: (length: 1)
        └── @ DefinedNode (location: (1,0)-(1,12))
            ├── lparen_loc: (1,8)-(1,9) = "("
            ├── value:
            │   @ IntegerNode (location: (1,9)-(1,11))
            │   ├── flags: decimal
            │   └── value: 42
            ├── rparen_loc: (1,11)-(1,12) = ")"
            └── keyword_loc: (1,0)-(1,8) = "defined?"