def __delitem__(self, key):
        self._purge_expired()

        # NOTE(flaper87): Delete the key. Using pop
        # since it could have been deleted already
        value = self._cache.pop(key, None)

        if value:
            try:
                # NOTE(flaper87): Keys with ttl == 0
                # don't exist in the _keys_expires dict
                self._keys_expires[value[0]].remove(key)
            except (__HOLE__, ValueError):
                pass
dataset/ETHPy150Open openstack/neutron/neutron/openstack/common/cache/_backends/memory.py/MemoryBackend.__delitem__