title: String function to strip the last comma
body: <p>Input</p>
  
  <pre><code>str = 'test1,test2,test3,'
  </code></pre>
  
  <p>Ouput </p>
  
  <pre><code>str = 'test1,test2,test3'
  </code></pre>
  
  <p>Requirement to strip the last occurence of ','</p>