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
  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 .func_inspect import getfullargspec
  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