Python 3 Encrypt / Decrypt files

index.py

import os
from cryptography.fernet import Fernet

def encrypt_or_decrypt_files(dir_path, should_encrypt, key):
    f = Fernet(key)
    for filename in os.listdir(dir_path):
        file_path = os.path.join(dir_path, filename)
        if os.path.isfile(file_path):
            with open(file_path, 'rb') as f_in:
                data = f_in.read()
            if should_encrypt:
                data = f.encrypt(data)
            else:
                data = f.decrypt(data)
            with open(file_path, 'wb') as f_out:
                f_out.write(data)
    print('Files processed successfully.')

dir_path = os.path.abspath('./test_dir2')
should_encrypt = True
key = b'VCh3rCt98y_x9opOx-X_Oz0iM1og4oSvBjJ5ogC2O9g='
encrypt_or_decrypt_files(dir_path, should_encrypt, key)