SessionStore object has no attribute 'get_session_cookie_age'

I have a Django project, everything goes well, but when I tried to handle the expiration of the session I got confused

In a test view print(request.session.get_session_cookie_age()) give me this error SessionStore' object has no attribute get_session_cookie_age

According to the documentation it should returns the value of the setting SESSION_COOKIE_AGE

Trying debugging with this code :

from django.contrib.sessions.models import Session
sk = request.session.session_key
s = Session.objects.get(pk=sk)
pprint(s.get_decoded())

>>> {'_auth_user_backend': 'django.contrib.auth.backends.ModelBackend',
 '_auth_user_hash': '055c9b751ffcc6f3530337321e98f9e5e4b8a623',
 '_auth_user_id': '6',
 '_session_expiry': 3600}

Here is the config :

Version Django = 2.0

Python 3.6.9

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django.contrib.postgres',
    'corsheaders',
    'rest_framework',
    'rest_framework.authtoken',
    'drf_yasg',
    'wkhtmltopdf',
]
MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'corsheaders.middleware.CorsMiddleware',
]

Thank's in advance

That functionality is not in Django 2.0, see here.