code: def _lookup_filetype(filename):
      for pattern in _FILETYPE_LOOKUP:
          if re.match(pattern, filename):
              return _FILETYPE_LOOKUP[pattern]
      raise ConversionError("Unrecognized extension!")
  
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 3 for calling a global function with example usage: _lookup_filetype(filename) and returns: _FILETYPE_LOOKUP