Clarify FLUSH on Couchbase bucket vs Memacached bucket

Clarify FLUSH on Couchbase bucket vs Memacached bucket -

"Enable flush allows you to flush data from a bucket. If the bucket is a couchbase bucket, then all items are immediately removed and the item count immediately becomes zero. If the bucket is a memcached bucket, then all Items are immediately marked as expired and, while the item count will not immediately become zero, the expired items cannot be retrieved and will removed as normal operations on the memached bucket continue."