Library Management App Error

Hi, I have a name error when I created Library Management app. This is with new frappe 4.5, I wonder if some class is removed in the new frappe bench.

import class also looks fine
from frappe.model.document import Document

Below is the error

File “/home/frappe/frappe-bench/apps/library_management/library_management/library_management/doctype/library_transaction/library_transaction.py”, line 18, in validate
msg = (“Article {0} {1} has not been recorded as returned since {2}”)
NameError: global name '
’ is not defined

Full server error code posted below

http://pastebin.com/aduzwNeQ

Add

from frappe import _

Cool. works like a breeze.