Progressbar not working in pytube?

Question

YouTube

Progressbar not working. appears only after the video is loaded.

import datetime
from pytube import YouTube
from pytube.cli import on_progress
def download_video(self, url, quality):
        yt = YouTube(url, on_progress_callback=on_progress)
        print("Video title: " + yt.title)
        print("Video views: " + str(yt.views))
        print("Video length: " + str(datetime.timedelta(seconds=yt.length)))
        print("Starting Download! \n")
        yt.streams.filter(res=quality, file_extension='mp4').first().download("Downloaded Videos")
        print("\n")
        print("Download Finished")