I'm looking for a simple solution using Python to store data as a flat file, such that each line is a string representation of an array that can be easily parsed.

I'm sure python has library for doing such a task easily but so far all the approaches I have found seemed like it would have been sloppy to get it to work and I'm sure there is a better approach. So far I've tried: 

* the array.toFile() method but couldn't figure out how to get it to work with nested arrays of strings, it seemed geared towards integer data.
* Lists and sets do not have a toFile method built in, so I would have had to parse and encode it manually.
* CSV seemed like a good approach but this would also require manually parsing it, and did not allow me to simply append new lines at the end - so any new calls the the CSVWriter would overwrite the file existing data.

I'm really trying to avoid using databases (maybe SQLite but it seems a bit overkill) because I'm trying to develop this to have no software prerequisites besides Python.