function for 'PHP function return value' when using image component inside flickity

plugin.php

/*
*
* Attribute name: data-flickity-lazyload-srcset
* Attribute value: PHP function return value - 
* function name: flickityLazySRCSET 
* function args: $field_name,$size
*/
function flickityLazySRCSET($field_name,$size) {
    
    $image = get_field($field_name);
    
    $image_src = ''; 
    
    if( $image ) {
        $image_src .= wp_get_attachment_image_srcset($image,$size);
    }
    
    return $image_src;
}