docs: def _parse_tokenize(self, rule):
          """Tokenizer for the policy language."""
  
          for token in self._TOKENIZE_RE.split(rule):
              # Skip empty tokens
              if not token or token.isspace():
                  continue
  
              # Handle leading parens on the token
              clean = token.lstrip('(')
              for i in range(len(token) - len(clean)):
                  yield '(', '('
  
              # If it was only parentheses, continue
              if not clean:
                  continue
              else:
                  token = clean
  
              # Handle trailing parens on the token
              clean = token.rstrip(')')
              trail = len(token) - len(clean)
  
              # Yield the cleaned token
              lowered = clean.lower()
              if lowered in ('and', 'or', 'not'):
                  # Special tokens
                  yield lowered, clean
              elif clean:
                  # Not a special token, but not composed solely of ')'
                  if len(token) >= 2 and ((token[0], token[-1]) in
                                          [('"', '"'), ("'", "'")]):
                      # It's a quoted string
                      yield 'string', token[1:-1]
                  else:
                      yield 'check', self._parse_check(clean)
  
              # Yield the trailing parens
              for i in range(trail):
                  yield ')', ')'