How to change the results URL to something else?

What is this, and where do I put this custom code?

Replacing with a static URL

add_filter( 'asp_results', function ( $results, $search_id, $is_ajax, $args ) {
	// Replaces each result URL with this
	$replace_with = 'https://google.com';

	// --- DO NOT CHANGE ANYTHING BELOW ---
	foreach ($results as $k=>$r) {
		// Ajax results link
		if ( isset($r->link) ) {
			$r->link = $replace_with;
		}
	}

	return $results;
}, 10, 4 );

Replacing multiple different URLs within the results

Enter the values to the $replace variable on line 7. On each line, the left side is the value to replace, with the value on the right side.

add_filter( 'asp_results', function ( $results, $search_id, $is_ajax, $args ) {
	// Array of original -> replacement links
	$replace = array(
		'websiteurl1.com' => 'google.com',
		'websiteurl2.com' => 'wikipedia.com',
		'websiteurl3.com' => 'bing.com'
	);

	// --- DO NOT CHANGE ANYTHING BELOW ---
	foreach ($results as $k=>&$r) {
		$link = $r->link ?? (isset($r->asp_guid) ? $r->asp_guid : '');
		if ( $link == '' )
			continue;
		$link = str_replace(array_keys($replace), array_values($replace), $link);

		// Ajax results link
		if ( isset($r->link) ) {
			$r->link = $link;
		}
	}

	return $results;
}, 10, 4 );

Parsing the url from post meta

What is this, and where do I put this custom code?

add_filter( 'asp_results', function ( $results, $search_id, $is_ajax, $args ) {
	// Change this variable to whatever meta key you are using
	$meta_key = 'custom_url';

	// --- DO NOT CHANGE ANYTHING BELOW ---
	foreach ($results as $k=>$r) {
		if ( function_exists('get_field') ) {
			$new_url = get_field( $meta_key, $r->id, true ); // ACF support
		} else {
			$new_url = get_post_meta( $r->id, $meta_key, true );
		}
		
		// Change only, if the meta is specified
		if ( !empty($new_url) ) {
			// Ajax results link
			if ( isset($r->link) ) {
				$r->link = $new_url;
			}
		}
	}

	return $results;
}, 10, 4 );