A loop that takes a while to run gives no feedback while it works. This step wraps a plain for loop so it prints a live progress bar instead, without changing anything else about the loop.

.. demo:: tutorial/step1

First, check the install. pip install progressbar2 (see :doc:`/installation`) puts a progressbar package on your path; confirm it with:

$ python -c "import progressbar; print(progressbar.__version__)"

If that prints a version number instead of an ImportError, you are ready.

The example wraps range(100) in progressbar.progressbar(...) and iterates the result exactly as it would iterate range(100) on its own. progressbar.progressbar() is a function, not the bar itself: it takes an iterable, hands back an iterator over the same values, and starts, updates and finishes a bar behind the scenes as that iterator is consumed. There is no separate call to make the bar advance or to mark it done.

That convenience comes from hiding the bar object entirely. The library also exposes that object directly as the ProgressBar class, which you construct yourself and update by calling a method whenever you decide progress has changed. progressbar.progressbar() is built on top of ProgressBar for the common case of running a loop over an iterable and showing a bar for it; when progress does not come from iterating something, you reach for ProgressBar directly, which the next step shows.

Next: :doc:`step2`.