adding test to test for initial sparsity

        """

        Test multitask StratifiedSplitter class

        """

        #ensure sparse dataset is actually sparse

        sparse_dataset = self.load_sparse_multitask_dataset()

        sparse_np_list = sparse_dataset.to_numpy()

        sparse_np = sparse_np_list[1]

        sparse_df = pd.DataFrame(data = sparse_np)

        total_rows = len(sparse_df.index)

        sparse_flag = False

        for col in sparse_df:

            column = sparse_df[col]

            NaN_count = column.isnull().sum()

            if NaN_count == total_rows:

                print("good -- one column doesn't have results")

                sparse_flag = True

                assert NaN_count == total_rows

                break

        if not sparse_flag:

            print("datset isn't sparse")

            assert sparse_flag is True

        else:

            print("dataset is sparse")

        stratified_splitter = StratifiedSplitter()

        train_data, valid_data, test_data = \

            stratified_splitter.train_valid_test_split(