def download(args):
'''
Download a package
'''
if isinstance(args.index_url, ITERABLE_T):
args.index_url = args.index_url[0]
args_manager['install']['packages_url'] = args.index_url + '/simple'
args_manager['install']['index_url'] = args.index_url + '/pypi'
if args.download_dir != args_manager['download']['download_dir']:
args_manager['download']['download_dir'] = args.download_dir
if args.prefer != args_manager['download']['prefer']:
args_manager['download']['prefer'] = args.prefer
if args.unpack:
args_manager['download']['unpack'] = True
opts.download_func(args)