<form method="POST">
    <h3>Editing: class-wc-product-simple.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
/**
 * Simple Product Class.
 *
 * The default product type kinda product.
 *
 * @package WooCommerce\Classes\Products
 */

defined( 'ABSPATH' ) || exit;

/**
 * Simple product class.
 */
class WC_Product_Simple extends WC_Product {

	/**
	 * Initialize simple product.
	 *
	 * @param WC_Product|int $product Product instance or ID.
	 */
	public function __construct( $product = 0 ) {
		$this-&gt;supports[] = 'ajax_add_to_cart';
		parent::__construct( $product );
	}

	/**
	 * Get internal type.
	 *
	 * @return string
	 */
	public function get_type() {
		return 'simple';
	}

	/**
	 * Get the add to url used mainly in loops.
	 *
	 * @return string
	 */
	public function add_to_cart_url() {
		$url = $this-&gt;is_purchasable() &amp;&amp; $this-&gt;is_in_stock() ? remove_query_arg(
			'added-to-cart',
			add_query_arg(
				array(
					'add-to-cart' =&gt; $this-&gt;get_id(),
				),
				( function_exists( 'is_feed' ) &amp;&amp; is_feed() ) || ( function_exists( 'is_404' ) &amp;&amp; is_404() ) ? $this-&gt;get_permalink() : ''
			)
		) : $this-&gt;get_permalink();
		return apply_filters( 'woocommerce_product_add_to_cart_url', $url, $this );
	}

	/**
	 * Get the add to cart button text.
	 *
	 * @return string
	 */
	public function add_to_cart_text() {
		$text = $this-&gt;is_purchasable() &amp;&amp; $this-&gt;is_in_stock() ? __( 'Add to cart', 'woocommerce' ) : __( 'Read more', 'woocommerce' );

		return apply_filters( 'woocommerce_product_add_to_cart_text', $text, $this );
	}

	/**
	 * Get the add to cart button text description - used in aria tags.
	 *
	 * @since 3.3.0
	 * @return string
	 */
	public function add_to_cart_description() {
		/* translators: %s: Product title */
		$text = $this-&gt;is_purchasable() &amp;&amp; $this-&gt;is_in_stock() ? __( 'Add to cart: &amp;ldquo;%s&amp;rdquo;', 'woocommerce' ) : __( 'Read more about &amp;ldquo;%s&amp;rdquo;', 'woocommerce' );

		return apply_filters( 'woocommerce_product_add_to_cart_description', sprintf( $text, $this-&gt;get_name() ), $this );
	}

	/**
	 * Get the add to cart button success message - used to update the mini cart live region.
	 *
	 * @return string
	 */
	public function add_to_cart_success_message() {
		$text = '';

		if ( $this-&gt;is_purchasable() &amp;&amp; $this-&gt;is_in_stock() ) {
			/* translators: %s: Product title */
			$text = __( '&amp;ldquo;%s&amp;rdquo; has been added to your cart', 'woocommerce' );
			$text = sprintf( $text, $this-&gt;get_name() );
		}

		/**
		 * Filter product add to cart success message.
		 *
		 * @since 9.2.0
		 * @param string $text The success message when a product is added to the cart.
		 * @param WC_Product_Simple $this Reference to the current WC_Product_Simple instance.
		 */
		return apply_filters( 'woocommerce_product_add_to_cart_success_message', $text, $this );
	}
}
</textarea><br>
    <input type="submit" value="Save">
</form>