code: def _genotype_in_background(rec, base_name, back_samples):
      
      def passes(rec):
          return not rec.FILTER or len(rec.FILTER) == 0
      return (passes(rec) and
              any(rec.genotype(base_name).gt_alleles == rec.genotype(back_name).gt_alleles
                  for back_name in back_samples))
docs: Check if the genotype in the record of interest is present in the background records.