Как сравнить два файла в python?

INPUT_FILENAME = 'file1'
BLACKLIST_FILENAME = 'file2'
OUTPUT_FILENAME = 'file3'

with open(BLACKLIST_FILENAME) as f:
    blacklist = [line.rstrip('\n') for line in f]

prev_line = None
with open(OUTPUT_FILENAME, 'w') as output_file:
    with open(INPUT_FILENAME) as input_file:
        for line in input_file:
            if line.rstrip('\n') in blacklist:
                prev_line = None
            else:
                if prev_line is not None:
                    output_file.write(prev_line)
                prev_line = line
        if prev_line is not None:
            output_file.write(prev_line)