If your program only ever uses a single tqdm instance at a time, then leave=True is great - you get a neat history of every bit of progress you've ever made.

However, if you use multiple tqdm instances, things don't work so well. Particularly, the remains of old, completed tqdm instances will be below the new active ones.

Solution for the simple case: when you create a new tqdm instance, clear out all the old rows below it (you do not want to do this earlier, because you do want to display the 100% until the next one is ready). Remember that the creator of the tqdm instances does not necessarily know about other pieces of code that create instances, so it has to be done in the library - nobody knows what to .clear()

However, this is not all that's needed for more advanced cases where bars may complete in any order - for example, I want to do a current-and-past parallel download presentation like aptitude does - essentially, every completed tqdm should be moved above all active tqdms (which then need to all be redrawn), and then forgotten.