title: How to insert a variable in href link in iPython markup
body: <p>I am using Ipython Notebook 2 </p>
  
  <p>I have a file name in variable which dynamically calculates the location and file name of file located in current directory, And I want to insert that variable in my markup to download it </p>
  
  <p><em>below is the code:</em></p>
  
  <pre><code>  result_file ="Revenue_per_city"+start_date+"_"+end_date+".xlsx
  </code></pre>
  
  <p><em>then my markup to download the file:</em></p>
  
  <pre><code> &lt;a href= {{result_file}}&gt; Click here to download the result&lt;/a&gt; 
  </code></pre>
  
  <p>but its not working as expected</p>