@ ProgramNode (location: (0...132))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...132))
    └── body: (length: 3)
        ├── @ DefNode (location: (0...39))
        │   ├── name: :m
        │   ├── name_loc: (4...5) = "m"
        │   ├── receiver: ∅
        │   ├── parameters: ∅
        │   ├── body:
        │   │   @ StatementsNode (location: (7...34))
        │   │   └── body: (length: 1)
        │   │       └── @ SingletonClassNode (location: (7...34))
        │   │           ├── locals: []
        │   │           ├── class_keyword_loc: (7...12) = "class"
        │   │           ├── operator_loc: (13...15) = "<<"
        │   │           ├── expression:
        │   │           │   @ SelfNode (location: (16...20))
        │   │           ├── body:
        │   │           │   @ StatementsNode (location: (22...29))
        │   │           │   └── body: (length: 1)
        │   │           │       └── @ ConstantWriteNode (location: (22...29))
        │   │           │           ├── name: :A
        │   │           │           ├── name_loc: (22...23) = "A"
        │   │           │           ├── value:
        │   │           │           │   @ NilNode (location: (26...29))
        │   │           │           └── operator_loc: (24...25) = "="
        │   │           └── end_keyword_loc: (31...34) = "end"
        │   ├── locals: []
        │   ├── def_keyword_loc: (0...3) = "def"
        │   ├── operator_loc: ∅
        │   ├── lparen_loc: ∅
        │   ├── rparen_loc: ∅
        │   ├── equal_loc: ∅
        │   └── end_keyword_loc: (36...39) = "end"
        ├── @ DefNode (location: (41...85))
        │   ├── name: :m
        │   ├── name_loc: (45...46) = "m"
        │   ├── receiver: ∅
        │   ├── parameters: ∅
        │   ├── body:
        │   │   @ StatementsNode (location: (48...80))
        │   │   └── body: (length: 1)
        │   │       └── @ SingletonClassNode (location: (48...80))
        │   │           ├── locals: []
        │   │           ├── class_keyword_loc: (48...53) = "class"
        │   │           ├── operator_loc: (54...56) = "<<"
        │   │           ├── expression:
        │   │           │   @ SelfNode (location: (57...61))
        │   │           ├── body:
        │   │           │   @ StatementsNode (location: (63...75))
        │   │           │   └── body: (length: 1)
        │   │           │       └── @ ClassNode (location: (63...75))
        │   │           │           ├── locals: []
        │   │           │           ├── class_keyword_loc: (63...68) = "class"
        │   │           │           ├── constant_path:
        │   │           │           │   @ ConstantReadNode (location: (69...70))
        │   │           │           │   └── name: :C
        │   │           │           ├── inheritance_operator_loc: ∅
        │   │           │           ├── superclass: ∅
        │   │           │           ├── body: ∅
        │   │           │           ├── end_keyword_loc: (72...75) = "end"
        │   │           │           └── name: :C
        │   │           └── end_keyword_loc: (77...80) = "end"
        │   ├── locals: []
        │   ├── def_keyword_loc: (41...44) = "def"
        │   ├── operator_loc: ∅
        │   ├── lparen_loc: ∅
        │   ├── rparen_loc: ∅
        │   ├── equal_loc: ∅
        │   └── end_keyword_loc: (82...85) = "end"
        └── @ DefNode (location: (87...132))
            ├── name: :m
            ├── name_loc: (91...92) = "m"
            ├── receiver: ∅
            ├── parameters: ∅
            ├── body:
            │   @ StatementsNode (location: (94...127))
            │   └── body: (length: 1)
            │       └── @ SingletonClassNode (location: (94...127))
            │           ├── locals: []
            │           ├── class_keyword_loc: (94...99) = "class"
            │           ├── operator_loc: (100...102) = "<<"
            │           ├── expression:
            │           │   @ SelfNode (location: (103...107))
            │           ├── body:
            │           │   @ StatementsNode (location: (109...122))
            │           │   └── body: (length: 1)
            │           │       └── @ ModuleNode (location: (109...122))
            │           │           ├── locals: []
            │           │           ├── module_keyword_loc: (109...115) = "module"
            │           │           ├── constant_path:
            │           │           │   @ ConstantReadNode (location: (116...117))
            │           │           │   └── name: :M
            │           │           ├── body: ∅
            │           │           ├── end_keyword_loc: (119...122) = "end"
            │           │           └── name: :M
            │           └── end_keyword_loc: (124...127) = "end"
            ├── locals: []
            ├── def_keyword_loc: (87...90) = "def"
            ├── operator_loc: ∅
            ├── lparen_loc: ∅
            ├── rparen_loc: ∅
            ├── equal_loc: ∅
            └── end_keyword_loc: (129...132) = "end"
