Error while creating library management app in frappe

i was working on library management system in frappe.
i was following tutorial from this site but in Controller validation for membership step when i make changes in and reload server, following error has occured:
Please help me to resolve the error…

@amandeep_kaur frappe.model.docstatus is not a module . and it’s true .

then, what i have to do to resolve this error ??

@amandeep_kaur can you share the code
In this link, code is given under types of doctype and file is also given in which we have to make the changes.

@amandeep_kaur I have been checking the apps core and it seems they are not using the frappe.model.docstatus anymore. just try to delete the row and also all the rows about docstatus.
may I ask you why are you creating doctypes this way ?

Hiii…I got the same error.
I am also creating LMS from Frappe Framework Tutorial
and got this error on same step. Then I tried from and error get resolved.
You can also try from this site.

Thank you, its working now.