class_docstr: kws task 
docstr: preprocess of data
docstr_tok: ["preprocess","of","data"]
code: def preprocess_batch(self, batch):
      """preprocess of data"""
      return batch
  
file_path: delta/delta/data/task/kws_cls_task.py
imports: import struct
  import numpy
  import delta.compat
  from delta import utils
  from delta.utils.register import registers
  from delta.data.task.base_speech_task import SpeechTask
  from delta.data.utils.htk_reader_lib import HtkReaderIO
label_desc: Use image node_id 6 for calling the KwsClsTask obj's underlying member method code with example usage: obj.preprocess_batch(batch) and returns: batch