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<meta charset="utf-8">
<head>
<title>Mezzo</title>
</head>
<script src="https://d3js.org/d3.v4.min.js"></script>
<body>
<button type="button" name="start_button" onclick="isAnimating=true; animateData(0);">start</button>
<button type="button" name="stop_button" onclick="isAnimating=false">stop</button>
<script src="script-mezzo.js" type="text/javascript"></script>
<script>
setTimeout(function() { animateData(0); }, 1000);
</script>
</body>
https://d3js.org/d3.v4.min.js