function get_the_post_thumbnail( $post = null, $size = 'post-thumbnail', $attr = '' ) {
    $post = get_post( $post );
    if ( ! $post ) {
        return '';
    }
    $post_thumbnail_id = get_post_thumbnail_id( $post );

    /**
     * Filters the post thumbnail size.
     *
     * @since 2.9.0
     * @since 4.9.0 Added the `$post_id` parameter.
     *
     * @param string|array $size    The post thumbnail size. Image size or array of width and height
     *                              values (in that order). Default 'post-thumbnail'.
     * @param int          $post_id The post ID.
     */
    $size = apply_filters( 'post_thumbnail_size', $size, $post->ID );

    if ( $post_thumbnail_id ) {

        /**
         * Fires before fetching the post thumbnail HTML.
         *
         * Provides "just in time" filtering of all filters in wp_get_attachment_image().
         *
         * @since 2.9.0
         *
         * @param int          $post_id           The post ID.
         * @param string       $post_thumbnail_id The post thumbnail ID.
         * @param string|array $size              The post thumbnail size. Image size or array of width
         *                                        and height values (in that order). Default 'post-thumbnail'.
         */
        do_action( 'begin_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size );
        if ( in_the_loop() )
            update_post_thumbnail_cache();
        $html = wp_get_attachment_image( $post_thumbnail_id, $size, false, $attr );

        /**
         * Fires after fetching the post thumbnail HTML.
         *
         * @since 2.9.0
         *
         * @param int          $post_id           The post ID.
         * @param string       $post_thumbnail_id The post thumbnail ID.
         * @param string|array $size              The post thumbnail size. Image size or array of width
         *                                        and height values (in that order). Default 'post-thumbnail'.
         */
        do_action( 'end_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size );

    } else {
        $html = '';
    }
    /**
     * Filters the post thumbnail HTML.
     *
     * @since 2.9.0
     *
     * @param string       $html              The post thumbnail HTML.
     * @param int          $post_id           The post ID.
     * @param string       $post_thumbnail_id The post thumbnail ID.
     * @param string|array $size              The post thumbnail size. Image size or array of width and height
     *                                        values (in that order). Default 'post-thumbnail'.
     * @param string       $attr              Query string of attributes.
     */
    return apply_filters( 'post_thumbnail_html', $html, $post->ID, $post_thumbnail_id, $size, $attr );
}