current_users = ['eric', 'willie', 'admin', 'erin', 'Ever']
new_users = ['sarah', 'Willie', 'PHIL', 'ever', 'Iona']

current_users_lower = [user.lower() for user in current_users]

for new_user in new_users:
    if new_user.lower() in current_users_lower:
        print(f"Sorry {new_user}, that name is taken.")
    else:
        print(f"Great, {new_user} is still available.")
