Another tweetable d3 animation

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<!DOCTYPE html>
<html lang="en">
  <head>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.13/d3.js"></script>
    <style>
    circle {
      fill:none;
      stroke: #222;
    }
    </style>
  </head>
  <body>
    <script src="scripts.js"></script>
  </body>
</html>
    

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.13/d3.js