docs: def generate_dataset(path, variant='20m', outputpath="."):
      """ Generates a hdf5 movielens datasetfile from the raw datafiles found at:
      https://grouplens.org/datasets/movielens/20m/
  
      You shouldn't have to run this yourself, and can instead just download the
      output using the 'get_movielens' funciton./
      """
      filename = os.path.join(outputpath, "movielens_%s.hdf5" % variant)
  
      if variant == '20m':
          ratings, movies = _read_dataframes_20M(path)
      elif variant == '100k':
          ratings, movies = _read_dataframes_100k(path)
      else:
          ratings, movies = _read_dataframes(path)
  
      _hfd5_from_dataframe(ratings, movies, filename)