code: def servicestore_factory(registry, database=None):
      
      database = database or 'mongodb'
      if database == 'mongodb':
          db = _mongodb(registry)
          store = MongodbServiceStore(collection=db.services)
      else:
          store = MemoryServiceStore()
      return store
docs: Creates a service store with the interface of :class:`twitcher.store.ServiceStore`.
      By default the mongodb implementation will be used.
  
      :return: An instance of :class:`twitcher.store.ServiceStore`.