docs: def multiprocessing_ppmap_worker(in_queue, out_queue, func, fixed_arg):
      """Worker for the :mod:`multiprocessing` ppmap implementation. Strongly
      derived from code posted on StackExchange by "klaus se":
      `<http://stackoverflow.com/a/16071616/3760486>`_.
  
      """
      while True:
          i, var_arg = in_queue.get()
          if i is None:
              break
          out_queue.put((i, func(i, fixed_arg, var_arg)))