public static function find($id, array $columns = [])
    {
        $model = static::getInstance();
        $key   = static::getModelKey($id, $model);
        $query = [
            'ConsistentRead' => true,
            'TableName'      => $model->getTable(),
            'Key'            => $key,
        ];
        if ( ! empty( $columns )) {
            $query['AttributesToGet'] = $columns;
        }
        $item = $model->client->getItem($query);
        $item = array_get($item->toArray(), 'Item');
        if (empty( $item )) {
            return null;
        }
        $item = $model->unmarshalItem($item);
        $model->fill($item);
        // Set the model id field.
        $model->setId($id);
        $model->exists = true;
        $model->syncOriginal();

        return $model;
    }