code: def get_user(self, user_id):
          
          try:
              return User.objects.get(id=user_id)
          except User.DoesNotExist:
              return None
docs: Returns a user, given his or her user id. Required for a custom authentication backend.
          Args:
              user_id
                  The user id of the user to fetch.
          Returns:
              User or None