assert_return(!(events & ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL);
assert_return(callback, -EINVAL);
assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
assert_return(!(events & ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL);
assert_return(callback, -EINVAL);
assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);