def logout_url(self, next):
        if hasattr(self.alt_login_form, 'logout_url'):
            return self.alt_login_form.logout_url(next)
        return next
Optional implement for alt_login_form.
dataset/ETHPy150Open uwdata/termite-data-server/web2py/gluon/contrib/login_methods/extended_login_form.py/ExtendedLoginForm.logout_url