Getting this error on the last line. I am not sure what to pass in the first argument...

File "/custom_modules/res_users_login_lowercase/res_users.py", line 16, in _login

    return super(Users, cls)._login(cls, db, login, password)

TypeError: unbound method _login() must be called with res.users instance as first argument (got MetaModel instance instead)

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08 from openerp import models, api, fields class Users(models.Model):

09    _inherit = 'res.users'

10     login = fields.Char(help='Used to log into the system. Case insensitive.',)

11 

12    @classmethod

13    def _login(cls, db, login, password):

14       """ Overload _login to lowercase the `login` before passing to the super """

15       login = login.lower()

16       return super(Users, cls)._login(cls, db, login, password)

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