@ ProgramNode (location: (1,0)-(4,3))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(4,3))
    └── body: (length: 1)
        └── @ CaseMatchNode (location: (1,0)-(4,3))
            ├── predicate:
            │   @ HashNode (location: (1,5)-(1,11))
            │   ├── opening_loc: (1,5)-(1,6) = "{"
            │   ├── elements: (length: 1)
            │   │   └── @ AssocNode (location: (1,6)-(1,10))
            │   │       ├── key:
            │   │       │   @ SymbolNode (location: (1,6)-(1,8))
            │   │       │   ├── flags: forced_us_ascii_encoding
            │   │       │   ├── opening_loc: ∅
            │   │       │   ├── value_loc: (1,6)-(1,7) = "a"
            │   │       │   ├── closing_loc: (1,7)-(1,8) = ":"
            │   │       │   └── unescaped: "a"
            │   │       ├── value:
            │   │       │   @ IntegerNode (location: (1,9)-(1,10))
            │   │       │   ├── flags: decimal
            │   │       │   └── value: 1
            │   │       └── operator_loc: ∅
            │   └── closing_loc: (1,10)-(1,11) = "}"
            ├── conditions: (length: 1)
            │   └── @ InNode (location: (2,0)-(3,6))
            │       ├── pattern:
            │       │   @ HashPatternNode (location: (2,3)-(2,16))
            │       │   ├── constant: ∅
            │       │   ├── elements: (length: 1)
            │       │   │   └── @ AssocNode (location: (2,4)-(2,8))
            │       │   │       ├── key:
            │       │   │       │   @ SymbolNode (location: (2,4)-(2,6))
            │       │   │       │   ├── flags: forced_us_ascii_encoding
            │       │   │       │   ├── opening_loc: ∅
            │       │   │       │   ├── value_loc: (2,4)-(2,5) = "a"
            │       │   │       │   ├── closing_loc: (2,5)-(2,6) = ":"
            │       │   │       │   └── unescaped: "a"
            │       │   │       ├── value:
            │       │   │       │   @ IntegerNode (location: (2,7)-(2,8))
            │       │   │       │   ├── flags: decimal
            │       │   │       │   └── value: 1
            │       │   │       └── operator_loc: ∅
            │       │   ├── rest:
            │       │   │   @ NoKeywordsParameterNode (location: (2,10)-(2,15))
            │       │   │   ├── operator_loc: (2,10)-(2,12) = "**"
            │       │   │   └── keyword_loc: (2,12)-(2,15) = "nil"
            │       │   ├── opening_loc: (2,3)-(2,4) = "{"
            │       │   └── closing_loc: (2,15)-(2,16) = "}"
            │       ├── statements:
            │       │   @ StatementsNode (location: (3,2)-(3,6))
            │       │   └── body: (length: 1)
            │       │       └── @ TrueNode (location: (3,2)-(3,6))
            │       ├── in_loc: (2,0)-(2,2) = "in"
            │       └── then_loc: ∅
            ├── consequent: ∅
            ├── case_keyword_loc: (1,0)-(1,4) = "case"
            └── end_keyword_loc: (4,0)-(4,3) = "end"