code: def use_setuptools(
          version=DEFAULT_VERSION, download_base=DEFAULT_URL,
          to_dir=DEFAULT_SAVE_DIR, download_delay=15):
      
      to_dir = os.path.abspath(to_dir)
  
      # prior to importing, capture the module state for
      # representative modules.
      rep_modules = 'pkg_resources', 'setuptools'
      imported = set(sys.modules).intersection(rep_modules)
  
      try:
          import pkg_resources
          pkg_resources.require("setuptools>=" + version)
          # a suitable version is already installed
          return
      except ImportError:
          # pkg_resources not available; setuptools is not installed; download
          pass
      except pkg_resources.DistributionNotFound:
          # no version of setuptools was found; allow download
          pass
      except pkg_resources.VersionConflict as VC_err:
          if imported:
              _conflict_bail(VC_err, version)
  
          # otherwise, unload pkg_resources to allow the downloaded version to
          #  take precedence.
          del pkg_resources
          _unload_pkg_resources()
  
      return _do_download(version, download_base, to_dir, download_delay)
docs: Ensure that a setuptools version is installed.
  
      Return None. Raise SystemExit if the requested version
      or later cannot be installed.