docs: function parseSelector() {
      while (!source.isAtEnd()) {
        var token = source.first();
  
        switch (token) {
          case '.':
            return cssSelector();
          case '#':
            return cssSelector();
          case '{':
            source.shift();
            if (useHash) {
              return hashSelectorContent();
            } else {
              return parseSelectorContent();
            }
  
          case '/':
            cssComment();
            break;
          case "'":
            singleQuoteString();
            break;
          case '"':
            doubleQuoteString();
            break;
          default:
            source.shift();
        }
      }
    }