Automattic / jetpack

extensions/blocks/image-compare/image-compare.php

<?php
/**
 * Image Compare Block.
 *
 * @since 8.6
 *
 * @package Jetpack
 */

namespace Automattic\Jetpack\Extensions\ImageCompare;

use Jetpack_AMP_Support;
use Jetpack_Gutenberg;

const FEATURE_NAME = 'image-compare';
const BLOCK_NAME   = 'jetpack/' . FEATURE_NAME;

/**
 * Registers the block for use in Gutenberg
 * This is done via an action so that we can disable
 * registration if we need to.
 */
function register_block() {
	jetpack_register_block(
		BLOCK_NAME,
		array( 'render_callback' => __NAMESPACE__ . '\load_assets' )
	);
}
add_action( 'init', __NAMESPACE__ . '\register_block' );

/**
 * Image Compare block registration/dependency declaration.
 *
 * @param array  $attr    Array containing the image-compare block attributes.
 * @param string $content String containing the image-compare block content.
 *
 * @return string
 */
function load_assets( $attr, $content ) {

This function seems to be duplicated in your project.

	Jetpack_Gutenberg::load_assets_as_required( FEATURE_NAME );
	if ( class_exists( 'Jetpack_AMP_Support' ) && Jetpack_AMP_Support::is_amp_request() ) {
		return render_amp( $attr );
	}

	return $content;
}


/**
 * Render image compare block for AMP
 *
 * @param array $attr Array containing the image-compare block attributes.
 *
 * @return string
 */
function render_amp( $attr ) {
	$img_before = $attr['imageBefore'];
	$img_after  = $attr['imageAfter'];

	return sprintf(
		'<amp-image-slider layout="responsive"%1$s%2$s> <amp-img id="%3$d" src="%4$s" alt="%5$s" layout="fill"></amp-img> <amp-img id="%6$d" src="%7$s" alt="%8$s" layout="fill"></amp-img></amp-image-slider>',
		! empty( $img_before['width'] ) ? ' width="' . absint( $img_before['width'] ) . '"' : '',
		! empty( $img_before['height'] ) ? ' height="' . absint( $img_before['height'] ) . '"' : '',
		absint( $img_before['id'] ),
		esc_url( $img_before['url'] ),
		esc_attr( $img_before['alt'] ),
		absint( $img_after['id'] ),
		esc_url( $img_after['url'] ),
		esc_attr( $img_after['alt'] )
	);
}