title: How to check how many times an element exists in a list
body: <p>I have a list like this:</p>
  <pre><code>[5,6,7,2,4,8,5,2,3]
  </code></pre>
  <p>and I want to check how many times each element exists in this list.</p>
  <p>what is the best way to do it in Python?</p>