Works, but template/ front-end integration very difficult

This plug-in works as advertised, but the integration to the front-end (in this case TwentySixteen) was very difficult. I spent hours on it, and ended up getting a consultation from a very skilled PHP developer to make it work. If you use twentysixteen, you’ll save hours with these code changes in the inc/template.php file in twentysixteen after Line 22:

[ Moderator note: code fixed. Please wrap code in the backtick character or use the code button. ]

function twentysixteen_entry_meta() {
	if ( 'post' === get_post_type() ) {
		$author_avatar_size = apply_filters( 'twentysixteen_author_avatar_size', 49 );
		// printf( '<span class="byline"><span class="author vcard">%1$s<span class="screen-reader-text">%2$s </span> <a href="%3$s">%4$s</a></span></span>',
		// 	get_avatar( get_the_author_meta( 'user_email' ), $author_avatar_size ),
		// 	_x( 'Author', 'Used before post author name.', 'twentysixteen' ),
		// 	esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ),
		// 	get_the_author()
		// );

		if ( class_exists( 'coauthors_plus' ) ) {
    // Get the Co-Authors for the post
			$co_authors = get_coauthors();
    // For each Co-Author, echo a wrapper div, their name, and their bio if they have one
			foreach ( $co_authors as $key => $co_author ) {
				$co_author_classes = array(
					'co-author-wrap',
					'co-author-number-' . ( $key + 1 ),
					);
				echo '<div class="' . implode( ' ', $co_author_classes ) . '">';
				echo get_avatar( $co_author->user_email, '80' );
				echo '<h3 class="author vcard"><span class="fn"><a>ID, $co_author->user_nicename ).'">'.$co_author->display_name.'</a></span></h3>';
				echo '</div>';
			}
		}

	}