def write_to_clf(clf_data, save_file):
    # Save dataset for text classification to file.
    """
    clf_data: List[List[str]] [[text1, label1],[text2,label2]...]
    file format: tsv, row: text + tab + label
    """
    with open(save_file, 'w', encoding='utf-8') as f:
        f.writelines("\n".join(["\t".join(str(r) for r in row) for row in clf_data]))