code: public static String parseProcessID(String fileName) {
          if (fileName == null || fileName.isEmpty()) {
              return null;
          }
          int pidIndex = fileName.indexOf(TIMESEPARATOR);
          int labelIndex = fileName.indexOf(LABELSEPARATOR);
  
          // If neither time separator or label separator present PID is the whole name
          if (pidIndex < 0 && labelIndex < 0) {
              return fileName;
          }
  
          // If no label separator then there's a time separator
          if (labelIndex < 0) {
              return fileName.substring(pidIndex + 1);
          }
  
          // If no time separator or it's a part of the label use label separator
          if (pidIndex < 0 || labelIndex < pidIndex) {
              return fileName.substring(0, labelIndex);
          }
  
          return fileName.substring(pidIndex + 1, labelIndex);
      }
docs: Retrieves the PID out of the directory name. (Qualifier 2)
  
  @param fileName
  @return