title: request.session.get('last_visit') yields None all the time
body: <p>I am recently into session and cookies. I comprehend session and cookies well in theory but i have one issue in understanding the code of session. It is about getting the last_visit by the user. The code is
  from the tangowithdjango.com </p>
  
  <pre><code>def index(request):
      context = RequestContext(request)
  
      category_list = Category.objects.all()
      context_dict = {'categories': category_list}
  
      for category in category_list:
          category.url = encode_url(category.name)
  
      page_list = Page.objects.order_by('-views')[:5]
      context_dict['pages'] = page_list
  
      #### NEW CODE ####
      if request.session.get('last_visit'):
          # The session has a value for the last visit
          last_visit_time = request.session.get('last_visit')
          visits = request.session.get('visits', 0)
  
          if (datetime.now() - datetime.strptime(last_visit_time[:-7], "%Y-%m-%d %H:%M:%S")).days &gt; 0:
              request.session['visits'] = visits + 1
              request.session['last_visit'] = str(datetime.now())
      else:
          # The get returns None, and the session does not have a value for the last visit.
          request.session['last_visit'] = str(datetime.now())
          request.session['visits'] = 1
      #### END NEW CODE ####
  
      # Render and return the rendered response back to the user.
      return render_to_response('rango/index.html', context_dict, context)
  </code></pre>
  
  <p>When i tried to understand what request.session.get('last_visit') does,  i get None all the time. What i don't understand is the key 'last_visit'. Is it default object inside session? If it is default in the session object then why it shows None every time in my terminal.</p>
  
  <p>Please someone make me understand the object passed inside get().</p>