code: def _organize_variants(samples, batch_id):
      
      caller_names = [x["variantcaller"] for x in samples[0]["variants"]]
      calls = collections.defaultdict(list)
      for data in samples:
          for vrn in data["variants"]:
              calls[vrn["variantcaller"]].append(vrn["vrn_file"])
      data = samples[0]
      vrn_files = []
      for caller in caller_names:
          fnames = calls[caller]
          if len(fnames) == 1:
              vrn_files.append(fnames[0])
          else:
              vrn_files.append(population.get_multisample_vcf(fnames, batch_id, caller, data))
      return caller_names, vrn_files
docs: Retrieve variant calls for all samples, merging batched samples into single VCF.