def insert(self, doc, synced=False):
        doc.id = self.get_next_id()
        doc.synced = synced
        try:
            self.db.docs.insert(doc)
        except Exception as e:
            raise DatabaseException(e)
        return doc
def is_overdue(self):
        """
        Returns True when the due date is in the past and the task has not
        yet been completed.
        """
        return not self.is_completed() and self.days_till_due() < 0