twentyseventeen_nav_menu_social_icons( string $item_output, WP_Post $item, int $depth, stdClass $args ): string

126function twentyseventeen_nav_menu_social_icons( $item_output, $item, $depth, $args ) {127	// Get supported social icons.128	$social_icons = twentyseventeen_social_links_icons();129 130	// Change SVG icon inside social links menu if there is supported URL.131	if ( 'social' === $args->theme_location ) {132		foreach ( $social_icons as $attr => $value ) {133			if ( false !== strpos( $item_output, $attr ) ) {134				$item_output = str_replace( $args->link_after, '</span>' . twentyseventeen_get_svg( array( 'icon' => esc_attr( $value ) ) ), $item_output );135			}136		}137	}138 139	return $item_output;140}