code: def get_region_bed(region, items, out_file, want_gzip=True):
      
      variant_regions = bedutils.population_variant_regions(items, merged=True)
      target = shared.subset_variant_regions(variant_regions, region, out_file, items)
      if not target:
          raise ValueError("Need BED input for strelka2 regions: %s %s" % (region, target))
      if not isinstance(target, six.string_types) or not os.path.isfile(target):
          chrom, start, end = target
          target = "%s-regions.bed" % utils.splitext_plus(out_file)[0]
          with file_transaction(items[0], target) as tx_out_file:
              with open(tx_out_file, "w") as out_handle:
                  out_handle.write("%s\t%s\t%s\n" % (chrom, start, end))
      out_file = target
      if want_gzip:
          out_file = vcfutils.bgzip_and_index(out_file, items[0]["config"])
      return out_file
docs: Retrieve BED file of regions to analyze, either single or multi-region.