title: Plotting the Digraph with graphviz in python from DOT file
body: <p>This is the <a href="http://graphviz.readthedocs.io/en/latest/api.html" rel="noreferrer">API reference</a> for <code>graphviz</code>. I could not find any method that generates a directed graph from an existing <code>dot</code> source file. Methods like <code>render</code> and <code>view</code> save in a new file. </p>
  
  <p>How can I display a graph from existing <code>dot</code> code?</p>