code: def skip(*filenames):
      """
      Detects if the Switchboard data preparation has already been done.
  
      Returns
      -------
      bool
          if True, the preparation phase can be skipped.
          if False, preparation must be done.
      """
      for filename in filenames:
          if not os.path.isfile(filename):
              return False
      return True
  
imports: import re
  import csv
  import logging
  import os
  from collections import defaultdict
  from speechbrain.dataio.dataio import merge_csvs
  from speechbrain.utils.data_utils import download_file, get_all_files
label_desc: Use image node_id 6 for calling a global function with example usage: skip() and returns: True, False