How to use the flask.session function in Flask

def consent():
    # redirect to next url when current user has already consented
    if current_user.has_consented:
        return redirect(session.pop("next_url", default_url()))
    form = ConsentForm()

    if form.validate_on_submit():
        current_user.consented_at = datetime.utcnow()
        current_user.profile_consent = True
        current_user.org_consent = True
        current_user.cookies_consent = True
        current_user.age_consent = True
        current_user.save()
        next_url = session.pop("next_url", default_url())
        return redirect(next_url)

    return {"form": form}

def wrap(*args, **kwargs):
        if 'logged_in' in session:
            return test(*args, **kwargs)
        else:
            flash('You need to login first.')
            return redirect(url_for('login'))
    return wrap

user_err_num = user.err_num
        if(user.jobnum=="None" or user.jobnum is None):
            return jsonify({'msg': login_user_inactivatesd, 'code': 34, 'data': ''})
        if user:
            if user.status is True:
                return jsonify({'msg': login_user_free_message, 'code': 35, 'data': ''})
            if user.check_password(password):
                if (user.is_free == True and user.freetime != None and user.err_num > 6 and (
                        datetime.datetime.now() - user.freetime).minute > 10):
                    return jsonify({'msg': login_user_fremm, 'code': 200, 'data': ''})
                user.is_login = True
                userlog = UserLoginlog(user=user.id, ip=ip, datatime=datetime.datetime.now())
                db.session.add_all([user, userlog])
                db.session.commit()
                login_user(user)
                session['username'] = username
                return jsonify({'msg': login_user_sucess_message, 'code': 200, 'data': ''})
            else:
                if (user.err_num >= 5):
                    if (user.freetime != 'None'):
                        if (datetime.datetime.now() - user.freetime).minute > 10:
                            user.err_num = user_err_num + 1
                            db.session.add(user)
                            db.session.commit()
                            return jsonify({'msg': login_password_error_message, 'code': 36, 'data': ''})
                        else:
                            user.err_num = 5
                            user.freetime = datetime.datetime.now()
                            user.is_free = True
                            db.session.add(user)
                            db.session.commit()
                            return jsonify({'msg': login_user_fremm, 'code': 36, 'data': ''})

def getFrontendContent(**params):
    """
    Deliver frontend content of module alarms

    :return: data of alarms
    """
    from emonitor.extensions import monitorserver

    if 'alarmfilter' not in session:
        session['alarmfilter'] = '7'
    if request.args.get('alarmfilter'):  # filter for alarms last x days, -1 no filter set
        session['alarmfilter'] = request.args.get('alarmfilter', '7')

    if 'area' in request.args:
        params['area'] = request.args.get('area')
    if 'state' in request.args:
        params['activeacc'] = request.args.get('state')

    if request.form.get('action') == 'updatealarm':
        if request.form.get('alarm_id') != 'None':  # update alarm
            alarm = Alarm.getAlarms(request.form.get('alarm_id'))
        else:  # create new alarm
            d = datetime.datetime.strptime('%s %s' % (request.form.get('edit_timestamp_date'), request.form.get('edit_timestamp_time')), "%d.%m.%Y %H:%M:%S")
            alarm = Alarm(d, request.form.get('edit_keyid'), 2, 0)
            db.session.add(alarm)
            params['activeacc'] = 1
        try:
            alarm.timestamp = datetime.datetime.strptime('%s %s' % (request.form.get('edit_timestamp_date'), request.form.get('edit_timestamp_time')), "%d.%m.%Y %H:%M:%S")

def logout():
    session.pop('user_id', None)
    return redirect('/pop')

@app.route('/logout')
def logout():
    session.clear()
    return redirect(url_for('index'))

def get_attached_folders(linked_object, include_empty=True, include_hidden=True, preload_event=False):
    """
    Return a list of all the folders linked to an object.

    :param linked_object: The object whose attachments are to be returned
    :param include_empty: Whether to return empty folders as well.
    :param include_hidden: Include folders that the user can't see
    :param preload_event: in the process, preload all objects tied to the
                          corresponding event and keep them in cache
    """
    from indico.modules.attachments.models.folders import AttachmentFolder

    folders = AttachmentFolder.get_for_linked_object(linked_object, preload_event=preload_event)

    if not include_hidden:
        folders = [f for f in folders if f.can_view(session.user)]

    if not include_empty:
        folders = [f for f in folders if f.attachments]

    return folders

@app.route('/logout')
def logout():
    logout_user()
    session.pop('openid', None)

    return redirect('/login')

@app.route('/add', methods=['POST'])
def add_post():
    page = int(request.form['index'])
    posts = Post.query.order_by(desc(Post.timestamp)).paginate(page, POSTS_PER_PAGE, False).items
    has_next = Post.query.order_by(desc(Post.timestamp)).paginate(page, POSTS_PER_PAGE, False).has_next

    if request.form['title'] == "" or request.form['body'] == "":
        flash('You have to fill all the inputs!','error')
        return render_template('show_posts.html', posts=posts, index=page, has_next = str(has_next), title=request.form['title'], body=request.form['body'], tags = request.form['tags'])

    if not session.get('logged_in'):
        abort(401)

    entry = request.form['body']

    r=re.compile(r'.*\[code (?P.{1,10})\](?P<code>.+)\[/code\].*', re.DOTALL)
    m=r.match(entry)

    if m is not None:
        lang = m.group('lang')
        code = m.group('code')

        lexer = get_lexer_by_name(lang, stripall=True)
        code = highlight(code, lexer, HtmlFormatter())

        front = entry[:entry.find('[code')]
        back = entry[entry.find('[/code]') + 7:]</code>

language_translation = LanguageTranslation(username='',
                                                   password='')
            langsdetected = language_translation.identify(txt)
            primarylang = langsdetected["languages"][0]['language']
            confidence = langsdetected["languages"][0]['confidence']

            lang = "I am %s confident that the language is %s" % (confidence, primarylang)
            session['langtext'] = lang

            allinfo['lang'] = lang
            allinfo['form'] = form
            return redirect(url_for('wlhome'))
        except WatsonException as err:
          allinfo['error'] = err

    allinfo['lang'] = session.get('langtext')
    allinfo['form'] = form
    return render_template('watson/wlindex.html', info=allinfo)