code: def calc_paired_insert_stats_save(in_bam, stat_file, nsample=1000000):
      
      if utils.file_exists(stat_file):
          with open(stat_file) as in_handle:
              return yaml.safe_load(in_handle)
      else:
          stats = calc_paired_insert_stats(in_bam, nsample)
          with open(stat_file, "w") as out_handle:
              yaml.safe_dump(stats, out_handle, default_flow_style=False, allow_unicode=False)
          return stats
docs: Calculate paired stats, saving to a file for re-runs.