Determining who hasn't renewed for the new year

member_renewals.py

import csv
import sys

DEBUG = False

# We process two input CSV files that have the following field names:
LAST_NAME_FIELD = 'Last Name'
FIRST_NAME_FIELD = 'First Name'
EMAIL_FIELD = 'Email Address'
CELL_PHONE_FIELD = 'Cell Phone Number'

def main(old_file, new_file):
    email_store = {}
    name_store = {}
    phone_number_store = {}
    
    try:
        with open(new_file) as csv_file:
            csv_reader = csv.DictReader(csv_file, delimiter=',')
            line_count = 0
            for row in csv_reader:
                if line_count == 0:
                    line_count = line_count + 1
                    continue
                full_name = '{} {}'.format(row[FIRST_NAME_FIELD], row[LAST_NAME_FIELD]).lower()
                email = row[EMAIL_FIELD].lower()
                phone_number = sanitize_phone_number(row[CELL_PHONE_FIELD])

                email_store[email] = full_name
                name_store[full_name] = email
                phone_number_store[phone_number] = full_name

                line_count += 1
            if DEBUG:
                print('Processed {} lines'.format(line_count))

        with open(old_file) as csv_file:
            csv_reader = csv.DictReader(csv_file, delimiter=',')
            line_count = 0
            for row in csv_reader:
                if line_count == 0:
                    line_count = line_count + 1
                    continue
                full_name = '{} {}'.format(row[FIRST_NAME_FIELD], row[LAST_NAME_FIELD]).lower()
                email = row[EMAIL_FIELD].lower()
                phone_number = sanitize_phone_number(row[CELL_PHONE_FIELD])

                line_count += 1

                if email in email_store:
                    if DEBUG:
                        print('{} in email store'.format(email))
                    continue

                if full_name in name_store:
                    if DEBUG:
                        print('{} in full name store'.format(full_name))
                    continue

                if phone_number in phone_number_store:
                    if DEBUG:
                        print('{} in phone number'.format(phone_number))
                    continue

                print('{},{},{},{}'.format(row[LAST_NAME_FIELD], row[FIRST_NAME_FIELD], row[EMAIL_FIELD], row[CELL_PHONE_FIELD]))
            
            if DEBUG:
                print('Processed {} lines'.format(line_count))
    except FileNotFoundError:
        print("ERROR: No such file exists;", old_file, new_file)
    except Exception as e:
        print("ERROR: Something went wrong:", e)

chars_to_sanitize = ['(', ')', ' ', '-', '.']

def sanitize_phone_number(str):
    for bad_char in chars_to_sanitize:
        str.replace(bad_char, '')
    return str

# Driver
main(sys.argv[1], sys.argv[2])