def replace_more_comments(self, limit=32, threshold=1):
        """Update the comment tree by replacing instances of MoreComments.

        :param limit: The maximum number of MoreComments objects to
            replace. Each replacement requires 1 API request. Set to None to
            have no limit, or to 0 to make no extra requests. Default: 32
        :param threshold: The minimum number of children comments a
            MoreComments object must have in order to be replaced. Default: 1
        :returns: A list of MoreComments objects that were not replaced.

        Note that after making this call, the `comments` attribute of the
        submission will no longer contain any MoreComments objects. Items that
        weren't replaced are still removed from the tree, and will be included
        in the returned list.

        """
        if self._replaced_more:
            return []

        remaining = limit
        more_comments = self._extract_more_comments(self.comments)
        skipped = []

        # Fetch largest more_comments until reaching the limit or the threshold
        while more_comments:
            item = heappop(more_comments)
            if remaining == 0:  # We're not going to replace any more
                heappush(more_comments, item)  # It wasn't replaced
                break
            elif len(item.children) == 0 or 0 < item.count < threshold:
                heappush(skipped, item)  # It wasn't replaced
                continue

            # Fetch new comments and decrease remaining if a request was made
            new_comments = item.comments(update=False)
            if new_comments is not None and remaining is not None:
                remaining -= 1
            elif new_comments is None:
                continue

            # Re-add new MoreComment objects to the heap of more_comments
            for more in self._extract_more_comments(new_comments):
                more._update_submission(self)  # pylint: disable=W0212
                heappush(more_comments, more)
            # Insert the new comments into the tree
            for comment in new_comments:
                self._insert_comment(comment)

        self._replaced_more = True
        return more_comments + skipped
Update the comment tree by replacing instances of MoreComments.

        :param limit: The maximum number of MoreComments objects to
            replace. Each replacement requires 1 API request. Set to None to
            have no limit, or to 0 to make no extra requests. Default: 32
        :param threshold: The minimum number of children comments a
            MoreComments object must have in order to be replaced. Default: 1
        :returns: A list of MoreComments objects that were not replaced.

        Note that after making this call, the `comments` attribute of the
        submission will no longer contain any MoreComments objects. Items that
        weren't replaced are still removed from the tree, and will be included
        in the returned list.