@cached_property
    def databases(self):
        if self._databases is None:
            self._databases = settings.DATABASES
        if self._databases == {}:
            self._databases = {
                DEFAULT_DB_ALIAS: {
                    'ENGINE': 'django.db.backends.dummy',
                },
            }
        if self._databases not in DEFAULT_DB_ALIAS:
            raise ImproperlyConfigured("You must define a '%s' database" % DEFAULT_DB_ALIAS)
        return self._databases
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/Django-1.6.10/django/db/utils.py/ConnectionHandler.databases/swapped operands of `not in`