title: How to calculate indegree and outdegree for a graph in directed graph SML code?
body: <p>I have a tuple like <code>(1,2),(3,4),(4,5)</code>. Edges: <code>1-&gt;2</code>, <code>3-&gt;4</code> and so on.</p>
  
  <p>How calculate in degree and out degree for each vertex?</p>