Python multiprocessing

Question

I wonder how python or os for that matter distributes task in multiprocessing.Pool(n).map(func, iterable). Does it divide all the tasks each one to each process in advance or processes start with a single task then get assigned new one when they are done with the current? And is there any priority or order followed in doing that?
https://code.sololearn.com/cmaEN3hjgaXf/?ref=app