code: public static String constructLogString(String message, String taskName, AbstractInvokable parent) {
  		return message + ":  " + taskName + " (" + (parent.getEnvironment().getTaskInfo().getIndexOfThisSubtask() + 1) +
  				'/' + parent.getEnvironment().getTaskInfo().getNumberOfParallelSubtasks() + ')';
  	}
docs: Utility function that composes a string for logging purposes. The string includes the given message,
  the given name of the task and the index in its subtask group as well as the number of instances
  that exist in its subtask group.
  
  @param message The main message for the log.
  @param taskName The name of the task.
  @param parent The task that contains the code producing the message.
  
  @return The string for logging.