Why "yield from" does not work as expected in all() or any()?

func1 is a function returning a generator while func2 and func3 are regular functions:

>>> type(func1())
<class 'generator'>
>>> type(func2())
All 3 ok !
<class 'NoneType'>

That's because:

ok3 = all((yield from yield_random()) for i in range(3))

is actually equivalent to:

def _gen():
    for i in range(3):
        r = yield from yield_random()
        yield r
ok3 = all(_gen())

This code doesn't yield anything since the yield from statement is encapsulated in a generator. You can even run it outside of a function, in your console for instance:

>>> all((yield from yield_random()) for i in range(3))
False

Though it probably doesn't do what you expect:

>>> list((yield from yield_random()) for i in range(3))
['OK', True, False, False]