@ ProgramNode (location: (2,0)-(3,21))
├── flags: ∅
├── locals: [:str]
└── statements:
    @ StatementsNode (location: (2,0)-(3,21))
    ├── flags: ∅
    └── body: (length: 2)
        ├── @ LocalVariableWriteNode (location: (2,0)-(2,18))
        │   ├── flags: newline
        │   ├── name: :str
        │   ├── depth: 0
        │   ├── name_loc: (2,0)-(2,3) = "str"
        │   ├── value:
        │   │   @ StringNode (location: (2,6)-(2,18))
        │   │   ├── flags: forced_binary_encoding
        │   │   ├── opening_loc: (2,6)-(2,7) = "\""
        │   │   ├── content_loc: (2,7)-(2,17) = "hello \\xFC"
        │   │   ├── closing_loc: (2,17)-(2,18) = "\""
        │   │   └── unescaped: "hello \xFC"
        │   └── operator_loc: (2,4)-(2,5) = "="
        └── @ CallNode (location: (3,0)-(3,21))
            ├── flags: newline
            ├── receiver:
            │   @ LocalVariableReadNode (location: (3,0)-(3,3))
            │   ├── flags: ∅
            │   ├── name: :str
            │   └── depth: 0
            ├── call_operator_loc: ∅
            ├── name: :=~
            ├── message_loc: (3,4)-(3,6) = "=~"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (3,7)-(3,21))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ RegularExpressionNode (location: (3,7)-(3,21))
            │           ├── flags: static_literal, forced_utf8_encoding
            │           ├── opening_loc: (3,7)-(3,8) = "/"
            │           ├── content_loc: (3,8)-(3,20) = "hello \\u{fc}"
            │           ├── closing_loc: (3,20)-(3,21) = "/"
            │           └── unescaped: "hello \\u{fc}"
            ├── closing_loc: ∅
            └── block: ∅
