'Insert things into the cached query.
This works as an upsert; if the thing already exists, it is updated. If
not, it is actually inserted.'

@classmethod
@tdb_cassandra.will_write
def insert(cls, mutator, key, columns, ttl=None):

    updates = dict(((key, json.dumps(value)) for (key, value) in columns.iteritems()))
    mutator.insert(cls._cf, key, updates, ttl=ttl)
