Difference between chain(*iterable) vs chain.from_iterable(iterable)

Question

I have been really fascinated by all the interesting iterators in itertools, but one confusion I have had is the difference between these two functions and why

Answer 1

chain(*foo(5)) unpacks the whole generator, packs it into a tuple and processes it then.

chain.from_iterable(foo(5)) queries the generator created from foo(5) value for value.

Try foo(1000000) and watch the memory usage go up and up.