PyMarc example with permission reading mode

PyMarc_permissive_reader.py

#!/usr/bin/python3
import os
import logging
from pymarc import MARCReader
from tqdm import tqdm

def main():
    # clean-up
    try:
        os.system('cls')
        os.system('del testing.log')
    except:
        pass

    # logging
    logging.basicConfig(filename='testing.log',level=logging.DEBUG)

    # progressbar
    total_records = 3715163
    pbar = tqdm(total=total_records)

    # open marc file and read contents
    # change the slice to limit files
    for filename in os.listdir('.//data'): # <------- check this limiter
        counter = 0
        with open(f'data/{filename}', 'rb') as fh:
            reader = MARCReader(fh, to_unicode=False, utf8_handling='ignore',
                                    permissive=True)

            # progressbar
            pbar.set_description(f"Reading {filename}")

            # loop through records
            for record in reader:
                # check for errors
                if record is None:
                    logging.info('BAD RECORD FOUND')
                
                # read through records
                counter += 15
                pbar.update(1)

        # log totals
        logging.info(f'{filename} total: {counter}')

    # finish
    pbar.set_description(f"Finished")

# top-level
if __name__ == "__main__":
    main()

When I try your python script, I get the following error:
[root@libvm15 publishToOCLC]# python pymarc_permissive_reader.py
File "pymarc_permissive_reader.py", line 26
with open(f'data/{filename}', 'rb') as fh:
^
SyntaxError: invalid syntax