Pythong Dictionaries

I can't figure out how to do this, I tried recursion but I'm horrible at it. I wouldn't mind trying this out iteratively either, I'm not looking for what's best, I'm just trying to get the job done.

Say I have a dictionary with dictionaries in them, dicts = {'a':{'b':{'c':None}, how would I add a dictionary to it assuming I didn't know how many dictionaries in it was?

I don't have the best understanding of it because the prof isn't that good.
Translation: I'm too much of a chickenshit to ask when I don't understand something and went home clueless.