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                    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 () {
       