code: function slide4() {
  		var slide = pptx.addNewSlide();
  		slide.addNotes('API Docs: https://gitbrent.github.io/PptxGenJS/docs/api-charts.html');
  		slide.addTable( [ [{ text:'Chart Examples: Lots of Bars (>26 letters)', options:gOptsTextL },gOptsTextR] ], gOptsTabOpts );
  
  		var arrDataHighVals = [
  			{
  				name  : 'TEST: getExcelColName',
  				labels: LETTERS.concat(['AA','AB','AC','AD']),
  				values: [-5,-3,0,3,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30 ]
  			}
  		];
  
  		var optsChart = {
  			x:0.5, y:0.5, w:'90%', h:'90%',
  			barDir: 'col',
  			title: 'Chart With >26 Cols',
  			showTitle: true,
  			titleFontSize: 20,
  			titleRotate: 10,
  			showCatAxisTitle: true,
  			catAxisTitle: "Letters",
  			catAxisTitleColor: "4286f4",
  			catAxisTitleFontSize: 14,
  
  			chartColors: ['EE1122'],
  			invertedColors: ['0088CC'],
  
  			showValAxisTitle: true,
  			valAxisTitle: "Column Index",
  			valAxisTitleColor: "c11c13",
  			valAxisTitleFontSize: 16,
  		};
  
  		// TEST `getExcelColName()` to ensure Excel Column names are generated correctly above >26 chars/cols
  		slide.addChart(pptx.charts.BAR, arrDataHighVals, optsChart);
  	}
docs: SLIDE 4: Bar Chart - Lots of Bars ---------------------------------------------------