class_docstr: A ParallelBackend which will execute all batches sequentially.
  
  Does not use/create any threading objects, and hence has minimal
  overhead. Used when n_jobs == 1.
class_docstr_tok: ["A","ParallelBackend","which","will","execute","all","batches","sequentially",".","Does","not","use\/create","any","threading","objects",",","and","hence","has","minimal","overhead",".","Used","when","n_jobs","==","1","."]
docstr: Schedule a func to be run
code: def apply_async(self, func, callback=None):
      """Schedule a func to be run"""
      result = ImmediateResult(func)
      if callback:
          callback(result)
      return result
  
imports: import gc
  import os
  import sys
  import warnings
  import threading
  from abc import ABCMeta, abstractmethod
  from .format_stack import format_exc
  from .my_exceptions import WorkerInterrupt, TransportableException
  from ._multiprocessing_helpers import mp
  from ._compat import with_metaclass
label_desc: Use image node_id 2 for calling the SequentialBackend obj's underlying member method code with example usage: obj.apply_async(func, callback) and returns: result