':return: A tuple with user and password strings.
TODO: I need a way to calculate the __len__ of this generator in order
to avoid the "iterable = list(iterable)" in pool.py'

def generator(self):

    for (user, pwd) in self._combo():
        (yield (user, pwd))
    user_chain = chain(self._user_from_file(), self._special_users())
    for user in unique_everseen(user_chain):
        if self.pass_eq_user:
            (yield (user, user))
        (yield (user, ''))
        for pwd in self._new_password_bruteforcer():
            (yield (user, pwd))
