How to use the dbutils.Review.fromBranch function in DBUtils

commit_list = []
    processed = set()

    while stack:
        sha1 = stack.pop()

        if sha1 not in commits and not isreachable(sha1):
            commits.add(sha1)
            commit_list.append(sha1)

            stack.extend([parent_sha1 for parent_sha1 in gitutils.Commit.fromSHA1(db, repository, sha1).parents if parent_sha1 not in processed])

        processed.add(sha1)

    branch = dbutils.Branch.fromName(db, repository, name)
    review = dbutils.Review.fromBranch(db, branch)

    if review:
        if review.state != "open":
            raise IndexException("""\
The review is closed and can't be extended.  You need to reopen it at
%s
before you can add commits to it.""" % review.getURL(db, user, 2))

        all_commits = [gitutils.Commit.fromSHA1(db, repository, sha1) for sha1 in reversed(commit_list)]

        tails = CommitSet(all_commits).getTails()

        if old not in tails:
            raise IndexException("""\
Push rejected; would break the review.

assert repository.id == repository_id

            if profiler: profiler.check("Branch.fromId: repository")

            base_branch = (Branch.fromId(db, base_branch_id, repository=repository)
                           if base_branch_id is not None else None)

            if profiler: profiler.check("Branch.fromId: base")

            branch = Branch(branch_id, repository, branch_name, head_commit_sha1, base_branch, tail_commit_sha1, type, archived)

            if load_review:
                from dbutils import Review

                branch.review = Review.fromBranch(db, branch)

                if profiler: profiler.check("Branch.fromId: review")

            return branch

def deleteBranch(db, user, repository, name, old):
    try:
        update(repository.path, "refs/heads/" + name, old, None)
    except Reject as rejected:
        raise IndexException(str(rejected))
    except Exception:
        pass

    branch = dbutils.Branch.fromName(db, repository, name)

    if branch:
        review = dbutils.Review.fromBranch(db, branch)

        if review:
            raise IndexException("This is Critic refusing to delete a branch that belongs to a review.")

        cursor = db.cursor()
        cursor.execute("SELECT COUNT(*) FROM reachable WHERE branch=%s", (branch.id,))

        ncommits = cursor.fetchone()[0]

        if branch.base:
            cursor.execute("UPDATE branches SET base=%s WHERE base=%s", (branch.base.id, branch.id))

        cursor.execute("DELETE FROM branches WHERE id=%s", (branch.id,))

        # Suppress the "user friendly" feedback if the push is performed by the
        # Critic system user, since there wouldn't be a human being reading it.

    @staticmethod
    def fromName(db, repository, name):
        return Review.fromBranch(db, Branch.fromName(db, repository, name))