docs: private static String removeSign(String str) {
  		StringBuilder sb = StrUtil.builder(str.length());
  		// 遍历字符串str,如果是汉字数字或字母，则追加到ab上面
  		int length = str.length();
  		for (int i = 0; i < length; i++) {
  			sb.append(charReg(str.charAt(i)));
  		}
  		return sb.toString();
  	}