title: how to clear the entire stdout?
body: <p>I want to print some strings in more than one line and then clear it and overwrite some other strings in stdout.</p>
  
  <p>I know about <code>\r</code> to return and overwrite the current line, but I want to clear every lines in stdout.</p>
  
  <p>and I also know about <code>os.system('clear')</code> to clear the screan but I don't want to clear the whole screen because it clears everything including the commands has been run before running this script and shell statuses.</p>