title: How to change arrowhead type?
body: <p>I want to simulate non-directional graphs with .dot. To that end, I want the arrowhead type to be "none". How do I set this?</p>
  
  <pre><code>"f" -&gt; "t" [label=2],[arrowhead=none]
  "m" -&gt; "d" [label=0],[arrowhead=none]
  </code></pre>
  
  <p>The above is not working.</p>