Consider the following generator function similar to the one that started this issue:

    from __future__ import generator_stop

    def myzip(*seqs):
        its = (iter(seq) for seq in seqs)
        while True:
            try:        
                yield tuple(next(it) for it in its)
            except RuntimeError:
                return

    g = myzip('abc', 'xyz')
    print([next(g) for i in range(5)]) # prints: [('a', 'x'), (), (), (), ()]

A print(list(g)) would cause a hang.