code: func (l *Scanner) Next() bool {
  	c, ok := l.nextChar()
  	if !ok {
  		return false
  	}
  	switch c {
  	case '"': // quoted-string;
  		return l.fetchQuotedString()
  
  	case '(': // comment;
  		return l.fetchComment()
  
  	case '\\', ')': // unexpected chars;
  		l.err = true
  		return false
  
  	default:
  		return l.fetchToken()
  	}
  }
docs: // Next scans for next token. It returns true on successful scanning, and false
  // on error or EOF.