Returns a generator of all labels in the store.

        If `include_deleted` is :const:`True`, labels that have been
        overwritten with more recent labels are also included.  If
        `content_id` is not :const:`None`, only labels for that
        content ID are retrieved; and then if `subtopic_id` is not
        :const:`None`, only that subtopic is retrieved, else all
        subtopics are retrieved.  If `content_id` is :const:`None` but
        `prefix` is not, then only labels with at least one content ID
        beginning with `prefix` will be returned.  The returned labels
        will always be q in sorted order, content IDs first, and with
        those with the same content, subtopic, and annotator IDs
        sorted newest first.

        :rtype: generator of :class:`Label`

def everything(self, include_deleted=False, content_id=None,
                   subtopic_id=None, prefix=None):
        '''Returns a generator of all labels in the store.

        If `include_deleted` is :const:`True`, labels that have been
        overwritten with more recent labels are also included.  If
        `content_id` is not :const:`None`, only labels for that
        content ID are retrieved; and then if `subtopic_id` is not
        :const:`None`, only that subtopic is retrieved, else all
        subtopics are retrieved.  If `content_id` is :const:`None` but
        `prefix` is not, then only labels with at least one content ID
        beginning with `prefix` will be returned.  The returned labels
        will always be q in sorted order, content IDs first, and with
        those with the same content, subtopic, and annotator IDs
        sorted newest first.

        :rtype: generator of :class:`Label`

        '''
        if content_id is not None:
            ranges = [((content_id,), (content_id,))]
        elif prefix is not None:
            # This is the cheap, easy, and wrong way to do this
            ranges = [((prefix,), (prefix + b'\xff',))]
        else:
            ranges = []
        labels = self.kvl.scan(self.TABLE, *ranges)
        labels = ifilter(self._filter_keys(content_id, prefix, subtopic_id),
                         labels)
        labels = imap(lambda p: self._label_from_kvlayer(*p), labels)
        if not include_deleted:
            labels = Label.most_recent(labels)
        return labels