越鸟巢Python嵌套词典问题，怎么解决

代码：
from collections import defaultdict

accountDetails = [
{"FirtsName": "JOHN", "LastName": "DENIS","date of Birth": "01-06-1992", "Account Number": "432524352345234", "Account Balance": "50000"},
{"FirtsName": "AKASH", "LastName": "MAHAJAN", "date of Birth": "04-02-1995","Account Number": "432524352345234", "Account Balance": "50000"},
{"FirtsName": "AMAN", "LastName": "RANA","date of Birth": "11-04-1996", "Account Number": "432524352345234", "Account Balance": "50000"},
{"FirtsName": "ANKUR", "LastName": "JAIN","date of Birth": "21-05-1990", "Account Number": "432524352345234", "Account Balance": "50000"},]d = defaultdict(lambda: defaultdict(dict))for item in accountDetails:
d[item['FirtsName']][item['LastName']][item['date of Birth']] = item

# get valid first namewhile True:
first_name_input = input('Enter First Name:\n').upper()
if first_name_input in d:
break
else:
print('Enter valid First Name')# get valid last namewhile True:
last_name_input = input('Enter Last Name:\n').upper()
if last_name_input in d[first_name_input]:
break
else:
print('Enter valid Last Name')
# get valid last namewhile True:
dob_input = input('Enter dob:\n')
if dob_input in d[first_name_input]:
break
else:
print('Enter valid dob')print(d[first_name_input][last_name_input])

人到中年，