title: Why is my igraph multilevel community modularity None?
body: <p>I created communities in igraph using:</p>
  
  <pre><code> g = Graph.TupleList(tupleMapping)
   layout = g.layout("rt")
   comm = g.community_multilevel()
  </code></pre>
  
  <p>But how can I access these cluster levels? I can print the communities but I want to access the different clustering levels.</p>
  
  <p>I tried print modularity using:</p>
  
  <pre><code>print comm._modularity
  </code></pre>
  
  <p>But my console returns null. Do you know why?</p>
  
  <p>Thanks.</p>