code: def run_mutation_aggregator(job, mutation_results, univ_options):
      
      # Setup an input data structure for the merge function
      out = {}
      for chrom in mutation_results['mutect'].keys():
          out[chrom] = job.addChildJobFn(merge_perchrom_mutations, chrom, mutation_results,
                                         univ_options).rv()
      merged_snvs = job.addFollowOnJobFn(merge_perchrom_vcfs, out, 'merged', univ_options)
      job.fileStore.logToMaster('Aggregated mutations for %s successfully' % univ_options['patient'])
      return merged_snvs.rv()
docs: Aggregate all the called mutations.
  
      :param dict mutation_results: Dict of dicts of the various mutation callers in a per chromosome
             format
      :param dict univ_options: Dict of universal options used by almost all tools
      :returns: fsID for the merged mutations file
      :rtype: toil.fileStore.FileID