code: def _run_ensemble(batch_id, vrn_files, config_file, base_dir, ref_file, data):
      
      out_vcf_file = os.path.join(base_dir, "{0}-ensemble.vcf".format(batch_id))
      out_bed_file = os.path.join(base_dir, "{0}-callregions.bed".format(batch_id))
      work_dir = "%s-work" % os.path.splitext(out_vcf_file)[0]
      if not utils.file_exists(out_vcf_file):
          _bcbio_variation_ensemble(vrn_files, out_vcf_file, ref_file, config_file,
                                    base_dir, data)
          if not utils.file_exists(out_vcf_file):
              base_vcf = glob.glob(os.path.join(work_dir, "prep", "*-cfilter.vcf"))[0]
              utils.symlink_plus(base_vcf, out_vcf_file)
      if not utils.file_exists(out_bed_file):
          multi_beds = glob.glob(os.path.join(work_dir, "prep", "*-multicombine.bed"))
          if len(multi_beds) > 0:
              utils.symlink_plus(multi_beds[0], out_bed_file)
      return {"variantcaller": "ensemble",
              "vrn_file": out_vcf_file,
              "bed_file": out_bed_file if os.path.exists(out_bed_file) else None}
docs: Run an ensemble call using merging and SVM-based approach in bcbio.variation