docs: public static String get(String regex, CharSequence content, int groupIndex) {
  		if (null == content || null == regex) {
  			return null;
  		}
  
  		// Pattern pattern = Pattern.compile(regex, Pattern.DOTALL);
  		final Pattern pattern = PatternPool.get(regex, Pattern.DOTALL);
  		return get(pattern, content, groupIndex);
  	}