code: def enable_parallel(processnum=None):
      
      global pool, dt, cut, cut_for_search
      from multiprocessing import cpu_count
      if os.name == 'nt':
          raise NotImplementedError(
              "jieba: parallel mode only supports posix system")
      else:
          from multiprocessing import Pool
      dt.check_initialized()
      if processnum is None:
          processnum = cpu_count()
      pool = Pool(processnum)
      cut = _pcut
      cut_for_search = _pcut_for_search
docs: Change the module's `cut` and `cut_for_search` functions to the
      parallel version.
  
      Note that this only works using dt, custom Tokenizer
      instances are not supported.