title: Python Error Message: TypeError: can only concatenate list (not "str") to list
body: <p>In my python code, I am getting below error. can someone please let me know how to solve this</p>
  <pre><code>key_split = key.rsplit('.', 1)
  return key_split  +  &quot;_thumbnail.png&quot;
  </code></pre>
  <h1></h1>
  <pre><code>TypeError: can only concatenate list (not &quot;str&quot;) to list
  </code></pre>