code: def _remove_comment_cols(self, header, rows):
      for col_index in reversed(range(len(header))):
          if header[col_index][0] == "#":
              del header[col_index]
              for row in rows:
                  del row[col_index]
  
imports: import atexit
  import csv
  import os
  import threading
  from collections import OrderedDict, deque
  from time import sleep
  import numpy
  from nnabla.config import nnabla_config
  from nnabla.logger import logger
  from nnabla.utils.communicator_util import current_communicator
  from six.moves import queue
  from .data_source import DataSource
  from .data_source_loader import FileReader, load
label_desc: Use image node_id 1 for calling the CsvDataSource obj's underlying member method code with example usage: obj._remove_comment_cols(header, rows) without return types