class_docstr: Callback used by joblib.Parallel's multiprocessing backend.
  
  This callable is executed by the parent process whenever a worker process
  has returned the results of a batch of tasks.
  
  It is used for progress reporting, to update estimate of the batch
  processing duration and to schedule the next batch of tasks to be
  processed.
code: def __call__(self, out):
      self.parallel.n_completed_tasks += self.batch_size
      this_batch_duration = time.time() - self.dispatch_timestamp
  
      self.parallel._backend.batch_completed(
          self.batch_size, this_batch_duration
      )
      self.parallel.print_progress()
      if self.parallel._original_iterator is not None:
          self.parallel.dispatch_next()
  
imports: from __future__ import division
  import os
  import sys
  from math import sqrt
  import functools
  import time
  import threading
  import itertools
  from numbers import Integral
  from contextlib import contextmanager
  import warnings
  from ...config import get_start_method
  from ._multiprocessing_helpers import mp
  from .format_stack import format_outer_frames
  from .logger import Logger, short_format_time
  from .my_exceptions import TransportableException, _mk_exception
  from .disk import memstr_to_bytes
  from ._parallel_backends import FallbackToBackend, MultiprocessingBackend, ThreadingBackend, SequentialBackend
  from ._compat import _basestring
  from ._parallel_backends import AutoBatchingMixin
  from ._parallel_backends import ParallelBackendBase
label_desc: Use image node_id 2 for calling the BatchCompletionCallBack obj's underlying member method code with example usage: obj.__call__(out) without return types