function lxb_rssm_coauthors( $post_id, $link_to = 'user_url', $label = 'display_name', $last_sep = "and " ) {

	$post_id = absint( $post_id );

	// If coauthors does not exist, bail with single author link.
	if( ! class_exists( 'CoAuthorsIterator' ) ) {

		$userdata = get_userdata( get_the_author_meta( 'ID' ) );

		$user_label = lxb_rssm_user_label( $userdata, $label );

		if( ! empty( $link_to ) ) {

			$link = lxb_rssm_user_link( $userdata, $link_to );

			return "<a href='$link'>$user_label</a>";

		}

		return $display_name;

	}

	// If coauthors does exist, instantiate it.
	$co = new CoAuthorsIterator( $post_id );

	// Start the output.
	$coauthors = '';

	// If we can iterate through the multi authors...
	if( method_exists( $co, 'iterate' ) ) {

		// Through each author...
		while( $co -> iterate() ) {

			// Put a comma between each, or an amp before the final one.

			$coauthors .= $co -> is_last() ? __( "$last_sep" ) : ',';

			$userdata = get_userdata( get_the_author_meta( 'ID' ) );

			$user_label = lxb_rssm_user_label( $userdata, $label );

			if( ! empty( $link_to ) ) {

				$link = lxb_rssm_user_link( $userdata, $link_to );

				// The display name wrapped in the user_url.
				$coauthors .= "<a href='$link'>$user_label</a> ";

			} else {

				$coauthors .= "$user_label ";

			}

		}

		// Tidy up the output
		$coauthors = ltrim( $coauthors, ', ' );
		$coauthors = ltrim( $coauthors, 'and ' );

		return $coauthors;
	}
}