 * We send out a heartbeat at all times to ensure we can
				 * reconnect with the main presentation window after reloads.
				 */
				function setupHeartbeat() {

					setInterval( () => {
						window.opener.postMessage( JSON.stringify({ namespace: 'reveal-notes', type: 'heartbeat'} ), '*' );
					}, 1000 );

				}

				function getTimings( callback ) {

					callRevealApi( 'getSlidesAttributes', [], function ( slideAttributes ) {
						callRevealApi( 'getConfig', [], function ( config ) {
							var tota