title: How to install python3.9 on linux ubuntu terminal?
body: <p>i Tried apt install python 3.9
  and it reply</p>
  
  <pre><code>Building dependency tree
  Reading state information... Done
  E: Unable to locate package python3.9
  E: Couldn't find any package by glob 'python3.9'
  E: Couldn't find any package by regex 'python3.9'
  </code></pre>