'Set the email opt-in preference.
Arguments:
user (User): The user model.
org (unicode): The org in the course key.
is_opted_in (bool): Whether the user is opted in or out of emails.
Returns:
None'

def _set_opt_in_pref(self, user, org, is_opted_in):

    update_email_opt_in(user, org, is_opted_in)
