@ ProgramNode (location: (0...21))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...21))
    └── body: (length: 2)
        ├── @ DefNode (location: (0...10))
        │   ├── name: :f
        │   ├── name_loc: (4...5) = "f"
        │   ├── receiver: ∅
        │   ├── parameters: ∅
        │   ├── body: ∅
        │   ├── locals: []
        │   ├── def_keyword_loc: (0...3) = "def"
        │   ├── operator_loc: ∅
        │   ├── lparen_loc: ∅
        │   ├── rparen_loc: ∅
        │   ├── equal_loc: ∅
        │   └── end_keyword_loc: (7...10) = "end"
        └── @ DefNode (location: (12...21))
            ├── name: :f
            ├── name_loc: (16...17) = "f"
            ├── receiver: ∅
            ├── parameters: ∅
            ├── body: ∅
            ├── locals: []
            ├── def_keyword_loc: (12...15) = "def"
            ├── operator_loc: ∅
            ├── lparen_loc: ∅
            ├── rparen_loc: ∅
            ├── equal_loc: ∅
            └── end_keyword_loc: (18...21) = "end"
