How to use the ghstack.logging.warning function in ghstack

"commit stack.  This is usually because of a botched "
                "rebase.  Please take a look at your git log and seek "
                "help from your local Git expert.".format(number))
        self.seen_ghnums.add(ghnum)

        logging.info("Pushing to #{}".format(number))

        # Compute the local and remote source IDs
        summary = commit.summary
        m_local_source_id = RE_GHSTACK_SOURCE_ID.search(summary)
        if m_local_source_id is None:
            # For BC, just slap on a source ID.  After BC is no longer
            # needed, we can just error in this case; however, this
            # situation is extremely likely to happen for preexisting
            # stacks.
            logging.warning(
                "Local commit has no ghstack-source-id; assuming that it is "
                "up-to-date with remote.")
            summary = "{}\nghstack-source-id: {}".format(summary, commit.source_id)
        else:
            local_source_id = m_local_source_id.group(1)
            if elab_commit.remote_source_id is None:
                # This should also be an error condition, but I suppose
                # it can happen in the wild if a user had an aborted
                # ghstack run, where they updated their head pointer to
                # a copy with source IDs, but then we failed to push to
                # orig.  We should just go ahead and push in that case.
                logging.warning(
                    "Remote commit has no ghstack-source-id; assuming that we are "
                    "up-to-date with remote.")
            else:
                if local_source_id != elab_commit.remote_source_id and not self.force:

# needed, we can just error in this case; however, this
            # situation is extremely likely to happen for preexisting
            # stacks.
            logging.warning(
                "Local commit has no ghstack-source-id; assuming that it is "
                "up-to-date with remote.")
            summary = "{}\nghstack-source-id: {}".format(summary, commit.source_id)
        else:
            local_source_id = m_local_source_id.group(1)
            if elab_commit.remote_source_id is None:
                # This should also be an error condition, but I suppose
                # it can happen in the wild if a user had an aborted
                # ghstack run, where they updated their head pointer to
                # a copy with source IDs, but then we failed to push to
                # orig.  We should just go ahead and push in that case.
                logging.warning(
                    "Remote commit has no ghstack-source-id; assuming that we are "
                    "up-to-date with remote.")
            else:
                if local_source_id != elab_commit.remote_source_id and not self.force:
                    raise RuntimeError(
                        "Cowardly refusing to push an update to GitHub, since it "
                        "looks another source has updated GitHub since you last "
                        "pushed.  If you want to push anyway, rerun this command "
                        "with --force.  Otherwise, diff your changes against "
                        "{} and reapply them on top of an up-to-date commit from "
                        "GitHub.".format(local_source_id))
                summary = RE_GHSTACK_SOURCE_ID.sub(
                    'ghstack-source-id: {}\n'.format(commit.source_id),
                    summary)

        # We've got an update to do!  But what exactly should we