def find_bookmark(self, bookmark, give_range=False):
        pos = 0
        for chunk in self.chunks:
            if chunk.bookmark and chunk.bookmark < bookmark:
                pos = chunk.pos
        if give_range:
            ret_next = 0
            for chunk in self.chunks:
                if ret_next == 1:
                    assert(chunk.pos > pos)
                    return pos, chunk.pos
                elif chunk.bookmark and chunk.bookmark > bookmark:
                    ret_next = 1
            return pos, None
        else:
            return pos
Given a model class or instance, returns a queryset of all instances of that model which have collection members in this manager's scope.
dataset/ETHPy150Open nandhp/python-imdb/imdb/chunkedfile.py/ChunkedFile.find_bookmark--crossover with--dataset/ETHPy150Open ithinksw/philo/philo/models/collections.py/CollectionMemberManager.with_model