def use_setuptools(<EOL>version=DEFAULT_VERSION, download_base=DEFAULT_URL,<EOL>to_dir=DEFAULT_SAVE_DIR, download_delay=<NUM_LIT:15>):
to_dir = os.path.abspath(to_dir)<EOL>rep_modules = '<STR_LIT>', '<STR_LIT>'<EOL>imported = set(sys.modules).intersection(rep_modules)<EOL>try:<EOL><INDENT>import pkg_resources<EOL>pkg_resources.require("<STR_LIT>" + version)<EOL>return<EOL><DEDENT>except ImportError:<EOL><INDENT>pass<EOL><DEDENT>except pkg_resources.DistributionNotFound:<EOL><INDENT>pass<EOL><DEDENT>except pkg_resources.VersionConflict as VC_err:<EOL><INDENT>if imported:<EOL><INDENT>_conflict_bail(VC_err, version)<EOL><DEDENT>del pkg_resources<EOL>_unload_pkg_resources()<EOL><DEDENT>return _do_download(version, download_base, to_dir, download_delay)<EOL>
Ensure that a setuptools version is installed.

Return None. Raise SystemExit if the requested version
or later cannot be installed.