new_contents: # import standard baseline models
  from polara.recommender.models import SVDModel
  from polara.recommender.models import CooccurrenceModel
  from polara.recommender.models import RandomModel
  from polara.recommender.models import PopularityModel
  # import data model
  from polara.recommender.data import RecommenderData
  # import data management routines
  from polara.datasets.movielens import get_movielens_data
  from polara.datasets.bookcrossing import get_bx_data
  from polara.datasets.netflix import get_netflix_data
  
subject: simplify import of main polara parts