            callback: function () {
                    hljs.initHighlightingOnLoad();
                }
            },
            { src: '../../slides/plugin/math/math.js', async: true }
                        ],
            keyboard: {
                /*
                67: function () {
                    RevealChalkboard.toggleNotesCanvas()
                }, // toggle notes canvas when 'c' is pressed
                66: function () {
                    RevealChalkboard.toggleChalkboard()
          