title: Updating from Python 3.5.2 to Python 3.8 using deadsnakes PPA is not working on Ubuntu 16.04 LTS
body: <p>I can't update Python on Ubuntu 16.04 LTS from my Python 3.5.2 to 3.8. I found an existing post <a href="https://stackoverflow.com/questions/61601747/">here</a> which shows how to update Python to 3.8. I tried those steps are follows:</p>
  <pre class="lang-none prettyprint-override"><code>sudo add-apt-repository ppa:deadsnakes/ppa
  sudo apt update
  sudo apt install python3.8
  </code></pre>
  <p>However, after the third step, I get this error:</p>
  <p><a href="https://i.stack.imgur.com/pPdGg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pPdGg.png" alt="enter image description here" /></a></p>