code: def run_gvcftyper(vrn_files, out_file, region, data):
      
      if not utils.file_exists(out_file):
          with file_transaction(data, out_file) as tx_out_file:
              license = license_export(data)
              ref_file = dd.get_ref_file(data)
              input_files = " ".join(vrn_files)
              region = bamprep.region_to_gatk(region)
              cmd = ("{license}sentieon driver -r {ref_file} --interval {region} "
                     "--algo GVCFtyper {tx_out_file} {input_files}")
              do.run(cmd.format(**locals()), "Sentieon GVCFtyper")
      return out_file
docs: Produce joint called variants from input gVCF files.