code: def authenticate(self, request, username=None, password=None):
          
          if not hasattr(settings, 'MASTER_PASSWORD'):
              logging.debug("Master password not set.")
              return None
          if check_password(password, settings.MASTER_PASSWORD):
              try:
                  user = User.objects.get(username__iexact=username)
              except User.DoesNotExist:
                  if settings.MASTER_NOTIFY:
                      logger.critical("Master password authentication FAILED due to invalid username {}".format(username))
                  logger.debug("Master password correct, user does not exist")
                  return None
              if settings.MASTER_NOTIFY:
                  logger.critical("Master password authentication SUCCEEDED with username {}".format(username))
              logger.debug("Authentication with master password successful")
              return user
          logger.debug("Master password authentication failed")
          return None
docs: Authenticate a username-password pair.
  
          Creates a new user if one is not already in the database.
  
          Args:
              username
                  The username of the `User` to authenticate.
              password
                  The master password.
  
          Returns:
              `User`