code: def _filename_pattern(ext):
      """Returns an re matching native or tfrecord files of format `ext`."""
      return r".*\.{}(\.tfrecord)?(\.gz)?".format(ext)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import re
  import sys
  import time
  from absl import app
  from absl import logging
  from third_party.nucleus.io import bed
  from third_party.nucleus.io import fastq
  from third_party.nucleus.io import gff
  from third_party.nucleus.io import sam
  from third_party.nucleus.io import vcf
label_desc: Use image node_id 2 for calling a global function with example usage: _filename_pattern(ext) and returns: str