title: add keys together in a dictionary
body: <p>Hei guys! I need help in a python program. I wanna make a method which returns the sum of the keys as a dictionary. But I get a error <code>"object is not iterable".</code></p>
  
  <pre><code>def totaltAntallSalg (dic) :
     s = sum (dic.keys)
     return s
  
  call_function = totaltAntallSalg({"Ahmed":2,"Nada":1, "hala":3 })
  </code></pre>
  
  <p>How can I solve  this problem?</p>
  
  <p>thanks in advance</p>