What is the most complex Python project you have ever built?

So I'm trying to get more comfortable as a Python programmer and I'm currently building a lot of smaller projects.<br><br>I have so many ideas for projects (for example, I want to build an app that will display a users reading and writing speed based on the words per minute average, something I imagine would be useful for others as well.)<br>I know the actual code isn't as important as the problem you're trying to solve but as a beginner I can't even imagine a project that requires more than 3k lines of code. What I mean is, I'm still not sure what exactly makes a project complex. I'm sure that if I tried to solve a real world problem, I'd find myself writing more lines of code than I currently am. I'm not sure what makes a project complex enough that it needs 10k lines of code. <br>To me that seems like a huge project.<br><br>I want to know what the most complex projects you have ever worked on using Python (or any other language) what were they, what made them so complex, how did you deal with debugging them, were you ever able to finish them?