'Remove things older than the specified timestamp.
Removing specific columns can cause tombstones to build up. When a row
has tons of tombstones fetching that row gets slow because Cassandra
must retrieve all the tombstones as well. Issuing a row remove with
the timestamp specified clears out all the columns modified before
that timestamp and somehow doesn\'t result in tombstones being left
behind. This behavior was verified via request tracing.'

@classmethod
@tdb_cassandra.will_write
def remove_older_than(cls, mutator, key, removal_timestamp):

    mutator.remove(cls._cf, key, timestamp=removal_timestamp)
