examples/research_projects/performer/run_mlm_performer.py/tokenize_function
    def tokenize_function(examples):
        # Remove empty lines
        examples = [line for line in examples if len(line) > 0 and not line.isspace()]
        return tokenizer(
            examples,
            return_special_tokens_mask=True,
            padding=padding,
            truncation=True,
            max_length=data_args.max_seq_length,
        )