How to use the quarry.web.user.get_user function in quarry

def api_set_meta():
    if get_user() is None:
        return "Authentication required", 401

    query = g.conn.session.query(Query).filter(Query.id == request.form['query_id']).one()

    if query.user_id != get_user().id:
        return "Authorization denied", 403

    if 'title' in request.form:
        query.title = request.form['title']
    if 'published' in request.form:
        query.published = request.form['published'] == '1'
    if 'description' in request.form:
        query.description = request.form['description']
    g.conn.session.add(query)
    g.conn.session.commit()
    return json.dumps({'id': query.id})

def unstar_query():
    if get_user() is None:
        return "Unauthorized access", 403
    query = g.conn.session.query(Query).get(request.form['query_id'])
    if query:
        star = g.conn.session.query(Star)\
            .filter(Star.query_id == request.form['query_id'])\
            .filter(Star.user_id == get_user().id)\
            .one()
        g.conn.session.delete(star)
        g.conn.session.commit()
        return ""
    else:
        return "Query not found", 404

def unstar_query():
    if get_user() is None:
        return "Unauthorized access", 403
    query = g.conn.session.query(Query).get(request.form['query_id'])
    if query:
        star = g.conn.session.query(Star)\
            .filter(Star.query_id == request.form['query_id'])\
            .filter(Star.user_id == get_user().id)\
            .one()
        g.conn.session.delete(star)
        g.conn.session.commit()
        return ""
    else:
        return "Query not found", 404

def api_run_query():
    if get_user() is None:
        return "Authentication required", 401
    text = request.form['text']
    query = g.conn.session.query(Query).filter(Query.id == request.form['query_id']).one()

    if query.user_id != get_user().id or \
            g.conn.session.query(UserGroup).filter(UserGroup.user_id == get_user().id) \
            .filter(UserGroup.group_name == 'blocked').first():
        return "Authorization denied", 403

    if query.latest_rev and query.latest_rev.latest_run:
        result = worker.run_query.AsyncResult(query.latest_rev.latest_run.task_id)
        if not result.ready():
            result.revoke(terminate=True)
            query.latest_rev.latest_run.status = QueryRun.STATUS_SUPERSEDED
            g.conn.session.add(query.latest_rev.latest_run)
            g.conn.session.commit()

    query_rev = QueryRevision(query_id=query.id, text=text)
    query.latest_rev = query_rev

    # XXX (phuedx, 2014/08/08): This deviates from the pre-existing

def new_query():
    if get_user() is None:
        return redirect("/login?next=/query/new")
    query = Query()
    query.user = get_user()
    g.conn.session.add(query)
    g.conn.session.commit()
    return redirect(url_for('query_show', query_id=query.id))

def fork_query(id):
    if get_user() is None:
        return redirect("/login?next=fork/{id}".format(id=id))
    query = Query()
    query.user = get_user()
    parent_query = g.conn.session.query(Query).filter(Query.id == id).one()
    query.title = parent_query.title
    query.parent_id = parent_query.id
    query.description = parent_query.description
    g.conn.session.add(query)
    g.conn.session.commit()

    query_rev = QueryRevision(query_id=query.id, text=parent_query.latest_rev.text)
    query.latest_rev = query_rev
    g.conn.session.add(query)
    g.conn.session.add(query_rev)
    g.conn.session.commit()
    return redirect(url_for('query_show', query_id=query.id))

def pref_set(key, value):
    if get_user() is None:
        return "Authentication required", 401

    get_preferences()[key] = (None if value == 'null' else value)
    return Response(json.dumps({'key': key, 'success': ''})), 201

def index():
    return render_template("landing.html", user=get_user())

def query_show(query_id):
    query = g.conn.session.query(Query).filter(Query.id == query_id).one()
    can_edit = get_user() is not None and get_user().id == query.user_id
    is_starred = False
    if get_user():
        is_starred = g.conn.session.query(func.count(Star.id))\
            .filter(Star.user_id == get_user().id)\
            .filter(Star.query_id == query_id).scalar() == 1
    jsvars = {
        'query_id': query.id,
        'can_edit': can_edit,
        'is_starred': is_starred,
        'published': query.published,
        'preferences': get_preferences()
    }

    if query.latest_rev and query.latest_rev.latest_run_id:
        jsvars['qrun_id'] = query.latest_rev.latest_run_id

def pref_get(key):
    if get_user() is None:
        return "Authentication required", 401

    if key in get_preferences():
        return Response(json.dumps({'key': key, 'value': get_preferences()[key]}))
    else:
        return Response(json.dumps({'key': key, 'error': 'novalue'}))