 treated as numerical targets
                 wine_description|wine_price
                 Exquisite wine!|100
                 Wine for budget shoppers|8

    Args:
        train_df(dataframe): Pandas dataframe
        text_column(str): name of column containing the text
        label_columns(list): list of columns that are to be treated as labels
        val_df(dataframe): file path to test dataframe.  If not supplied,
                               10% of documents in training df will be
               