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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _parse_args():
 """Parse sys.argv arguments"""


    token_file = os.path.expanduser('~/.nikeplus_access_token')

    parser = argparse.ArgumentParser(description='Export NikePlus data to CSV')

    parser.add_argument('-t', '--token', required=False, default=None,
                        help=('Access token for API, can also store in file %s'
                        ' to avoid passing via command line' % (token_file)))
    parser.add_argument('-s', '--since', type=_validate_date_str,
                        help=('Only process entries starting with YYYY-MM-DD '
                              'and newer'))

    args = vars(parser.parse_args())

    if args['token'] is None:
        try:
            with open(token_file, 'r') as _file:
                access_token = _file.read().strip()
        except IOError:
            print 'Must pass access token via command line or store in file %s' % (
                                                                    token_file)
            sys.exit(-1)

        args['token'] = access_token

    return args