public function add($key, $super_column, $column, $value=1,
                        $consistency_level=null) {
        $packed_key = $this->pack_key($key);
        $cp = $this->create_column_parent($super_column);
        $counter = new CounterColumn();
        $counter->name = $this->pack_name($column);
        $counter->value = $value;
        return $this->pool->call("add", $packed_key, $cp, $counter,
            $this->wcl($consistency_level));
    }