title: How to find the last occurrence of an item in a Python list
body: <p>Say I have this list:</p>
  
  <pre><code>li = ["a", "b", "a", "c", "x", "d", "a", "6"]
  </code></pre>
  
  <p>As far as help showed me, there is not a builtin function that returns the last occurrence of a string (like the reverse of <code>index</code>). So basically, how can I find the last occurrence of <code>"a"</code> in the given list?</p>