Hello. I made a program that displays a list of customers and their info but does not show anything that does not fit in the parameters laid out in the code. I have added more customers to my list and for some reason I'm getting the following error:

 File "/home/ec2-user/environment/Week 4/Lab 4 Part 2.py", line 175, in <module>   customers = list(map(display, customer_list))  File "/home/ec2-user/environment/Week 4/Lab 4 Part 2.py", line 171, in display   return "{:>30}".format(check_first_name(first_name))+"{:>30}".format(check_last_name(last_name)) + "{:>30}".format(check_zip(Zip)) + "{:>30}".format(check_phone(ph)) TypeError: unsupported format string passed to NoneType.__format__ 

I originally had 8 different customers in my list and I changed it to 25. It was working with 8. I'm not sure what I need to change. My current code is below.

import pandas as pd from random import randint # lists of data first_names = [   "Tom",   "Susan",   "Zack",   "Stephan",   "Louis",   "Billy",   "Linda",   "Raul",   "Robert",   "Paul",   "Xavier",   "Taylor",   "Jonny",   "Johnathan",   "Patrick",   "Moira",   "Timothy",   "Javier",   "156331.1",   "Tulip",   "45",   "Bryce",   "Donna",   "Randy",   "Duane"] last_names = [   "Johnson",   "Armstrong",   "Jackson",   "Arnold",   "Davis",   "Watson",   "Garfield",   "Stoneking",   "Davidson",   "Grande",   "1365122",   "1",   "Surandon",   "Johnathan",   "Vaughan",   "Brenner",   "987",   ".6",   "Poppy.1",   "Winn",   "Nicholson",   "Warner",   "Brown",   "Blue",   "Johnson"] zip_code = [   "32654",   "96536-1987",   "456",   "36965953",   "96584",   "963852",   "xc",   "95632",   "36412365",   "45986-4212",   "13654785",   "96458",   "78459",   "98745845458454",   "33333",   "x",   "96864",   "12365-4584",   "99545",   "98641",   "964",   "1.2",   "98521",   "32654",   "12546"] phone = [   "965-698-4596",   "8954621365",   "85963545",   "6985",   "tys",   "985-986-4685",   "897-695-4512",   "8975462136",   "986-654-2136",   "9658741532",   "965-415-35215",   "968-745-5432",   "458.65.6954",   "451.652.1253",   "695-458-4512",   "3264125041",   "969-854-7845",   "652-451-3625",   "3201203252",   "32362",   "659410253",   "985475130",   "9658654121",   "3261451201",   "965-745-4851"]   # prameters for customer list customer_list = [] for i in range(len(first_names)):   customer_list.append({"First Name": first_names[i],              "Last Name": last_names[i],              "Zip Code": zip_code[i],              "Phone": phone[i]}) # checking to see if first and name is string of letters def check_first_name(first_names):   for first_name in first_names:     if not first_name.isalpha():       first_name = ""     else:       return first_names def check_last_name(last_names):   for last_name in last_names:     if not last_name.isalpha():       last_name = ""     else:       return last_names # check to see if Zip is in right format and is int def check_zip(zip_code):   while "-" in zip_code:     zip_code = zip_code.replace("-", "")   if not zip_code.isdigit():     return ""   zip_code = int(zip_code)   if zip_code < 9:     return ""   else:     return zip_code # checks phone to see if in right format and is integer def check_phone(phone):   while "-" in phone:     phone = phone.replace("-", "")   if len(phone) < 10:     return ""   elif not phone.isdecimal():     return ""   else:     return phone       customer_list.append({"First Name": first_names[i],              "Last Name": last_names[i],              "Zip Code": zip_code[i],              "Phone": phone[i]}) def display(customer):   first_name = customer['First Name']   last_name = customer['Last Name']   Zip = customer['Zip Code']   ph = customer['Phone']   return "{:>30}".format(check_first_name(first_name))+"{:>30}".format(check_last_name(last_name)) + "{:>30}".format(check_zip(Zip)) + "{:>30}".format(check_phone(ph)) print("{:>30}{:>30}{:>30}{:>30}".format(   "First name", "Last name", "Zip code", "Phone number")) customers = list(map(display, customer_list)) for customer in customers:   print(customer)