old_contents: from django.http import Http404
  from django.contrib.auth.models import User
  from pytask.profile.models import Notification
  
  def get_notification(nid, user):
      """ if notification exists, and belongs to the current user, return it.
      else return None.
      """
  
      user_notifications = user.notification_sent_to.filter(is_deleted=False).order_by('sent_date')
      current_notifications = user_notifications.filter(uniq_key=nid)
      if user_notifications:
          current_notification = current_notifications[0]
  
          try:
              newer_notification = current_notification.get_next_by_sent_date(sent_to=user, is_deleted=False)
              newest_notification = user_notifications.reverse()[0]
              if newest_notification == newer_notification:
                  newest_notification = None
          except Notification.DoesNotExist:
              newest_notification, newer_notification = None, None
  
          try:
              older_notification = current_notification.get_previous_by_sent_date(sent_to=user, is_deleted=False)
              oldest_notification = user_notifications[0]
              if oldest_notification == older_notification:
                  oldest_notification = None
          except:
              oldest_notification, older_notification = None, None
  
          return newest_notification, newer_notification, current_notification, older_notification, oldest_notification
  
      else:
          return None, None, None, None, None
  
  def get_user(uid):
  
      try:
          user = User.objects.get(id=uid)
      except User.DoesNotExist:
          raise Http404
  
      if user.is_active:
          return user
      else:
          raise Http404
  
  
new_contents: from django import shortcuts
  from django.http import Http404
  from django.contrib.auth.models import User
  from pytask.profile.models import Notification
  
  def get_notification(nid, user):
      """ if notification exists, and belongs to the current user, return it.
      else return None.
      """
  
      user_notifications = user.notification_sent_to.filter(is_deleted=False).order_by('sent_date')
      current_notifications = user_notifications.filter(uniq_key=nid)
      if user_notifications:
          current_notification = current_notifications[0]
  
          try:
              newer_notification = current_notification.get_next_by_sent_date(sent_to=user, is_deleted=False)
              newest_notification = user_notifications.reverse()[0]
              if newest_notification == newer_notification:
                  newest_notification = None
          except Notification.DoesNotExist:
              newest_notification, newer_notification = None, None
  
          try:
              older_notification = current_notification.get_previous_by_sent_date(sent_to=user, is_deleted=False)
              oldest_notification = user_notifications[0]
              if oldest_notification == older_notification:
                  oldest_notification = None
          except:
              oldest_notification, older_notification = None, None
  
          return newest_notification, newer_notification, current_notification, older_notification, oldest_notification
  
      else:
          return None, None, None, None, None
  
  def get_user(uid):
  
      user = shortcuts.get_object_or_404(User, pk=uid)
  
      if user.is_active:
          return user
      else:
          raise Http404
  
subject: Use django shortcut for raising 404s.