code: def update_task_ids(self, encoder_vocab_size):
      
      for idx, task in enumerate(self.task_list):
        task.set_task_id(idx + encoder_vocab_size)
        tf.logging.info("Task %d (%s) has id %d." %
                        (idx, task.name, task.task_id))
docs: Generate task_ids for each problem.
  
      These ids correspond to the index of the task in the task_list.
  
      Args:
        encoder_vocab_size: the size of the vocab which is used to compute
          the index offset.