You know that moment where you had working code, and now it has stopped working, and you aren't quite sure what you've changed? You made a lot of good changes since your last commit, and you don't want to throw those away, but you need to find the erroneous change. This is where PyCharm's local history functionality really shines. You can right click (or ctrl-click) on a file or a workspace, and see a timeline of all changes, with a visual diff of each change. This can help you quickly hunt down errors, without throwing away your good changes. It's particularly helpful if you're experimented with many different variations for a specific block of code.