title: Is it possible to use d3.svg.symbol along with svg.marker
body: <p>Currently I am using markers to plot arrow in between paths.</p>
  
  <pre><code>var def = viz.append("svg:defs")
      .selectAll(".traffic")
      .data(["green", "yellow", "red"]) ;// grey 
  
      def.enter().append("svg:marker")
      .attr("id", String)
      .attr("class","traffic")
      .attr("viewBox", "0 0 8 10")
      .append("svg:polyline")
      .attr("points","0,0 8,5 0,10 1,5")
      .attr("fill", String)
      ;
  </code></pre>
  
  <p>and my path will call the markers like </p>
  
  <pre><code>viz.selectAll("path").attr("marker-mid", "url(#red)");
  </code></pre>
  
  <p>Is is possible to use d3.svg.symbol() instead of marker or along with marker ?</p>