Hi @kintaro,
run_lm_fine_tuning.py is now renamed to run_language_modeling.py , you can fine it here.
The data file can be in one of the two formats

Line by line: which means each example is on it’s own line seperated by \n. Set the --line_by_line command line argument
Or just a plain text file from which examples will be sampled .

This notebook 4 also walks through how a language model can be trained.