'Return whether to use memcache for this key.
Args:
key: Key instance.
options: ContextOptions instance, or None.
Returns:
True if the key should be cached in memcache, False otherwise.'

def _use_memcache(self, key, options=None):

    flag = ContextOptions.use_memcache(options)
    if (flag is None):
        flag = self._memcache_policy(key)
    if (flag is None):
        flag = ContextOptions.use_memcache(self._conn.config)
    if (flag is None):
        flag = True
    return flag
