To find the difference between two files

find_diff.py

FIRST_FILE_PATH = 'simple_1.csv'
SECOND_FILE_PATH = 'simple_2.csv'
OUTPUT_FILE_PATH = 'file_diff.csv'

with open(FIRST_FILE_PATH, 'r') as first_file, open(SECOND_FILE_PATH, 'r') as second_file:
    first_reader = first_file.readlines()
    second_reader = second_file.readlines()

with open(OUTPUT_FILE_PATH, 'w+') as output:
    for line in first_reader:
        if line not in second_reader:
            output.write(line)