title: how to update dagreD3 node style without re-rendering graph
body: <p>Is there a way to change the style of a node without having to re-render the graph, like in the last code block below?</p>
  
  <pre><code>var g = new dagreD3.graphlib.Graph({compound:true})
    .setGraph({}).setDefaultEdgeLabel(function() { return {}; });
  
  g.setNode('step1', {label: 'Step 1', style: "fill:gray" });
  g.setNode('step2', {label: 'Step 2', style: "fill:gray" });
  g.setNode('step3', {label: 'Step 3', style: "fill:gray" });
  
  g.setEdge('step1', 'step2');
  g.setEdge('step2', 'step3');
  
  var render = new dagreD3.render();
  var svg = d3.select("svg").append("g");
  render(d3.select("svg g"), g);
  
  // example node color change
  function sleep(ms) {
    return new Promise(resolve =&gt; setTimeout(resolve, ms));
  }
  sleep(2000).then(() =&gt; {
    // ????? another way to do this without calling render()?
    g.node('step1').style = "fill:blue";
    render(d3.select("svg g"), g);
  });
  </code></pre>