@ ProgramNode (location: (0...25))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...25))
    └── body: (length: 1)
        └── @ CaseNode (location: (0...25))
            ├── predicate:
            │   @ SymbolNode (location: (5...7))
            │   ├── opening_loc: (5...6) = ":"
            │   ├── value_loc: (6...7) = "a"
            │   ├── closing_loc: ∅
            │   └── unescaped: "a"
            ├── conditions: (length: 1)
            │   └── @ InNode (location: (8...21))
            │       ├── pattern:
            │       │   @ AlternationPatternNode (location: (11...16))
            │       │   ├── left:
            │       │   │   @ ConstantReadNode (location: (11...12))
            │       │   │   └── name: :B
            │       │   ├── right:
            │       │   │   @ ConstantReadNode (location: (15...16))
            │       │   │   └── name: :C
            │       │   └── operator_loc: (13...14) = "|"
            │       ├── statements:
            │       │   @ StatementsNode (location: (19...21))
            │       │   └── body: (length: 1)
            │       │       └── @ SymbolNode (location: (19...21))
            │       │           ├── opening_loc: (19...20) = ":"
            │       │           ├── value_loc: (20...21) = "d"
            │       │           ├── closing_loc: ∅
            │       │           └── unescaped: "d"
            │       ├── in_loc: (8...10) = "in"
            │       └── then_loc: ∅
            ├── consequent: ∅
            ├── case_keyword_loc: (0...4) = "case"
            └── end_keyword_loc: (22...25) = "end"
