Not every loop hands you a clean iterable to wrap -- sometimes you need to decide for yourself when and where progress has moved on. This step drops the wrapper from the previous step and drives a ProgressBar by hand.

.. demo:: tutorial/step2

The previous step gave range(100) to progressbar.progressbar() and let it manage everything. Here, the loop instead opens a ProgressBar() as a context manager -- with progressbar.ProgressBar() as bar: -- and, on each pass through its own for loop, calls bar.update(i + 1) to report the new value itself. The with block starts the bar on entry and finishes it on exit, the same start and finish progressbar.progressbar() did implicitly in step 1; the difference is that this code decides when update() is called, so it works just as well when progress doesn't come from iterating a sequence at all.

Next: :doc:`step3`.