title: Two-way arrows possible in force directed graph?
body: <p>I have created a graph similar to this force directed graph: <a href="http://bl.ocks.org/d3noob/5141278" rel="nofollow noreferrer">http://bl.ocks.org/d3noob/5141278</a> :</p>
  
  <p><img src="https://i.stack.imgur.com/2dJhc.png" alt="enter image description here"></p>
  
  <p>Using the link as an example: Sarah is linked to James and James is linked to Sarah. Instead of cluttering up the page with two arrows (one in each direction), is there a way to make it have just one arrow with triangles on both ends?</p>