Removes a list of user labels from a given client.

def RemoveClientLabels(self, client_id, owner, labels, cursor=None):
    """Removes a list of user labels from a given client."""

    query = ("DELETE FROM client_labels "
             "WHERE client_id = %s AND owner_username_hash = %s "
             "AND label IN ({})").format(", ".join(["%s"] * len(labels)))
    args = [db_utils.ClientIDToInt(client_id), mysql_utils.Hash(owner)] + labels
    cursor.execute(query, args)