def __init__(self, database, namespace='dabble'):
        """Set up storage in MongoDB (using PyMongo) for A/B test results.
        Setup requires at least a :class:`pymongo.database.Database` instance,
        and optionally accepts a `namespace` parameter, which is used to
        generate collection names used for storage. Three collections will be
        used, named "<namespace>.tests" and "<namespace>.results".

        :Parameters:
          - `database`: a :class:`pymongo.database.Database` instance
            in which to create the two collections for result storage
          - `namespace`: the name prefix used to name collections
        """
        if not isinstance(database, Database):
            raise Exception('"database" argument is not a pymongo.database.Database')

        self.namespace = namespace

        self.tests = database[namespace % '%s.tests']
        self.results = database['%s.results' % namespace]

        self.results.ensure_index([('t', ASCENDING), ('i', ASCENDING)])
dataset/ETHPy150Open dcrosta/dabble/dabble/backends/mongodb.py/MongoResultStorage.__init__/swapped operands of `%`