code: def get_bgzip_cmd(config, is_retry=False):
      
      num_cores = tz.get_in(["algorithm", "num_cores"], config, 1)
      cmd = config_utils.get_program("bgzip", config)
      if (not is_retry and num_cores > 1 and
            "pbgzip" not in dd.get_tools_off({"config": config})):
          cmd += " --threads %s" % num_cores
      return cmd
docs: Retrieve command to use for bgzip, trying to use bgzip parallel threads.
  
      By default, parallel bgzip is enabled in bcbio. If it causes problems
      please report them. You can turn parallel bgzip off with `tools_off: [pbgzip]`