code: private void require(String delim) throws SAXException, IOException {
          int length = delim.length();
          char[] ch;
  
          if (length < dataBuffer.length) {
              ch = dataBuffer;
              delim.getChars(0, length, ch, 0);
          } else {
              ch = delim.toCharArray();
          }
  
          for (int i = 0; i < length; i++) {
                  require(ch[i]);
          }
      }
docs: Require a string to appear, or throw an exception.
  <p>
  <em>Precondition:</em> Entity expansion is not required.
  <p>
  <em>Precondition:</em> data buffer has no characters that will get sent
  to the application.