title: Write dictionary values in an excel file
body: <p>I have a dictionary with multiple values for each key. I add the values using the following code:</p>
  
  <pre><code>d.setdefault(key, []).append(values)
  </code></pre>
  
  <p>The key value correspondence looks like this:</p>
  
  <pre><code>a -el1,el2,el3
  b -el1,el2
  c -el1
  </code></pre>
  
  <p>I need to loop thru the dictionary and write in an excel file:</p>
  
  <pre class="lang-none prettyprint-override"><code>Column 1  Column 2
  a         el1
            el2
            el3
  b         el1
            el2
  c         el1
  </code></pre>
  
  <p>For writing in the excel file I use xlsxwriter. I need help looping separately thru the dictionary, because after writing the key and I don't need to write it again until I finish all the corresponding values.</p>