title: Unsupported operand type(s) for +: 'dict' and 'int'
body: <p>Bit of a weird one!</p>
  
  <p>Could anyone shed some light on this <code>TypeError</code> message?</p>
  
  <pre><code>csvRow.append(len(calls["outbound"] + len(calls["inbound"])))
  TypeError: unsupported operand type(s) for +: 'dict' and 'int'
  </code></pre>
  
  <p>When I do the following, I get no issues and it runs as expected:</p>
  
  <pre><code>totalinbound = len(calls["inbound"])
  totaloutbound = len(calls["outbound"])
  csvRow.append(totalinbound + totaloutbound)
  </code></pre>