title: Multiple graphs inside Graphviz DOT file
body: <p>I have this Graphviz DOT graph:</p>
  <pre><code>digraph unit_test {
      label=&quot;Unit test&quot;
      
      edge [fillcolor=&quot;#a6cee3&quot; color=&quot;#1f78b4&quot;]
  
      node[shape=&quot;ellipse&quot; style=&quot;filled&quot; fillcolor=&quot;#1f77b4&quot;]
          start
          end
      node[shape=&quot;box&quot; style=&quot;filled&quot; fillcolor=&quot;#ff7f0e&quot;]
          process
          
      subgraph cluster_process {
          label = &quot;Major logic&quot;
          process
      }
      
      start -&gt; process
      process -&gt; end
      
  }
  </code></pre>
  <p>The above renders as:</p>
  <p><a href="https://i.stack.imgur.com/7kHLm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7kHLm.png" alt="First graph" /></a></p>
  <p>I have this second graph:</p>
  <pre><code>digraph details {
      label = &quot;Process details&quot;
      
      edge [fillcolor=&quot;#a6cee3&quot; color=&quot;#1f78b4&quot;]
      
      node[shape=&quot;ellipse&quot; style=&quot;filled&quot; fillcolor=&quot;#1f77b4&quot;]
          start
          end
      node[shape=&quot;box&quot; style=&quot;filled&quot; fillcolor=&quot;#ff7f0e&quot;]
          details
      
      subgraph cluster_details {
          label = &quot;Details&quot;
          details
      }
      
      start -&gt; details
      details -&gt; end
  }
  </code></pre>
  <p>Which renders to:</p>
  <p><a href="https://i.stack.imgur.com/69aPx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/69aPx.png" alt="Second graph" /></a></p>
  <h2>Problem</h2>
  <p>When I put the above two graphs inside the same DOT file named <code>supporting.dot</code> and I run <code>dot -Tpng -o supporting.png supporting.dot</code> command, terminal prints out some jiberish and the output image file won't contain both graphs, it just contains the first one. Is it possible to use multiple graphs inside a single DOT file? If so, what am I missing?</p>
  <p><a href="https://i.stack.imgur.com/N8FYK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/N8FYK.png" alt="Terminal output" /></a></p>