Export csv _lottery_pn_answers

/**
 * Add the custom column to the exporter and the exporter column menu.
 *
 * @param array $columns
 * @return array $columns
 */
function add_export_column( $columns ) {
    $columns['_lottery_pn_answers'] = 'Meta: _lottery_pn_answers';
    return $columns;
}
add_filter( 'woocommerce_product_export_column_names', 'add_export_column' );
add_filter( 'woocommerce_product_export_product_default_columns', 'add_export_column' );

/**
 * Provide the data to be exported for one item in the column.
 *
 * @param mixed $value (default: '')
 * @param WC_Product $product
 * @return mixed $value - Should be in a format that can be output into a text file (string, numeric, etc).
 */
function add_export_data( $value, $product ) {
    $value = $product->get_meta( '_lottery_pn_answers', true, 'edit' );
    return maybe_serialize ( $value );
}
// Filter you want to hook into will be: 'woocommerce_product_export_product_column_{$column_slug}'.
add_filter( 'woocommerce_product_export_product_column__lottery_pn_answers', 'add_export_data', 10, 2 );