def prepare_filtering_date(self, val):
        if isinstance(val, datetime):
            val = val.strftime('%a, %d %b %Y %H:%M:%S GMT')
        else:
            val = '"%s"' % val
        return {'If-Modified-Since': val}
dataset/ETHPy150Open freakboy3742/pyxero/xero/basemanager.py/BaseManager.prepare_filtering_date/original