Генераторы

gen.py

def _(f,*args):
    yield f
    for a in args:
        if type(a)==str:
            yield a
        else:
            # yield from a
            for b in a:
                yield b

for a in _('f',_('g','a','c'),'b'):
    print (a)


def gen(x):
    while True:
        yield x
        x+1

for b in gen(10):
    print (b)
    if b>10:
        break