Keeping track with a progress bar

Recipe Difficulty: Easy

Python Version: 2.7 or 3.5

Operating System: Any

Long-running scripts are unfortunately commonplace when processing data measured in gigabytes or terabytes. While your script may be processing this data smoothly, a user may think it's frozen after three hours with no indication of progress. Luckily, several developers have built an incredibly simple progress bar library, giving us little excuse for not incorporating this into our code.