One of my favourite things in the Python standard library is the ThreadPoolExecutor. It is a very simple way to run a bunch of tasks in parallel, such as converting or repacking a whole bunch of image files from one format to another. You write a pure function that takes two arguments, the input and output file names, and does the conversion. Then you submit a bunch of tasks (basically function and argument pairs) and the executor runs them with maximal parallelism.I decided to implement this in Pystd. To make things simpler it does not yet support futures for return...