def on_delete(self, forced):
        if not forced and self.handler is not None and not self.is_closed:
            self.promote()
        else:
            self.close()
Generate a list of all cache dirs, directories of the form:
dataset/ETHPy150Open mrjoes/tornadio/tornadio/pollingsession.py/PollingSession.on_delete--crossover with--dataset/ETHPy150Open Sage-Bionetworks/synapsePythonClient/synapseclient/cache.py/Cache._cache_dirs