
    <div id="controls">
    </div>
    <div id="viz">
      <svg style="width:600px;height:600px;" ></svg>
    </div>
    <script>
      var PromiseWrapper = (xhr, d) => new Promise(resolve => xhr(d, (p) => resolve(p)));

      Promise
        .all([
          PromiseWrapper(d3.json, "../data/world.geojson"),
          PromiseWrapper(d3.csv, "../data/cities.csv")
        ])
        .then(resolve => {
          createMap(resolve[0], resolve[1]);
        });

      function createMap(countries, cities) {
   