def getlast(self, key, default=None):
        values = self.getlist(key)
        return values[-1] if values else default
create and write archive data to index.json
dataset/ETHPy150Open uwdata/termite-data-server/web2py/gluon/storage.py/Storage.getlast--crossover with--dataset/ETHPy150Open SMFOSS/CheesePrism/tests/test_index.py/IndexTestCase.test_write_datafile