class_docstr: Message sent from a worker to the pool to notify the pool about completed tasks
  along with meta data needed to fetch and deserialize results stored in the shared memory
  
  Parameters
  ----------
  `worker_id` : int
      Id of the worker that completed the task.
  `context_i` : int
      Index identifying the callback in the order of parallel callbacks passed to pool.
  `scheduled_i` : int
      Ordinal of the batch that tasks corresponds to.
  `minibatch_i` : int
      Computation of batch might be split into number of minibatches, this is the number
      that identifies which consecutive part of the batch it is.
  `batch_meta` :  nvidia.dali._multiproc.shared_batch.SharedBatchMeta
      Serialized result of the task.
  `exception`
      Exception if the task failed.
code: def is_failed(self):
      return self.exception is not None
  
imports: from typing import Optional
  from nvidia.dali.types import SampleInfo
  from nvidia.dali._multiproc.struct_message import Structure
label_desc: Use image node_id 4 for calling the CompletedTask obj's underlying member method code with example usage: obj.is_failed() and returns: unknown