Item of a list is not defined in an ‘if’ statement

  if-statement, list, python-3.x

This code should warn me if an element in the second list is already in the first, after having put the first in lower case.

current_users = ['id_1','id_2','id_3', 'ID_4', 'id_5']
current_users_case = [current_user_case.lower() for current_user_case in current_users]

new_users = ['id_5','id_4','id_7', 'id_8', 'id_9']

for new_user in new_users:
  if new_user == current_user_case:
    print("Sorry, ID already taken")
    print("ID available")

I get this error message:

Traceback (most recent call last):
  File "", line 2, in <module>
    from c5n9ss import *
  File "/home/runner/C5py/", line 11, in <module>
    if new_user == current_user_case:
NameError: name 'current_user_case' is not defined

But if I test the first two lines in the Python shell, I get the lowered list correctly.

I don’t understand the error I get.

Source: Python-3x Questions