ЖЖ пароли и вообще security

import argparse
import hashlib

parser = argparse.ArgumentParser(description='Searches passwords in https://haveibeenpwned.com/Passwords database.')
parser.add_argument('passwords', metavar='TEST', type=str, help='text file with passwords to test, one per line, utf-8')
parser.add_argument('database', metavar='DATABASE', type=str, help='the downloaded text file with sha-1:count')
args = parser.parse_args()

def search(f: object, pattern: str) -> str:

    def search(left, right: int) -> str:
        if left >= right:
            return None

        middle = (left + right) // 2
        if middle == 0:
            f.seek(0, 0)
            test = f.readline()
        else:
            f.seek(middle - 1, 0)
            _ = f.readline()
            test = f.readline()

        if test.upper().startswith(pattern):
            return test
        elif left == middle:
             return None
        elif pattern < test:
            return search(left, middle)
        else:
            return search(middle, right)

    f.seek(0, 2)
    return search(0, f.tell())

fsource = open(args.passwords)
fdatabase = open(args.database)
source_lines = fsource.readlines()
for l in source_lines:
    line = l.strip()
    hash_object = hashlib.sha1(line.encode("utf-8"))
    pattern = hash_object.hexdigest().upper()
    print("%s:%s" % (line, str(search(fdatabase, pattern)).strip()))
fsource.close()
fdatabase.close()