def get_docs_to_commit(self):
        try:
            spec = {'synced': False}
            fields = {'_id': 0}
            cur = self.db.docs.find(spec, fields)
        except Exception as e:
            raise DatabaseException(e)
        return list(cur)
def getAp2(self):
        ret =math.acos(((self.getLenp1() * self.getLenp1() + self.getLenp3() * self.getLenp3()) - self.getLenp2() * self.getLenp2()) / (2* self.getLenp1() * self.getLenp3()))
        return ret