def get_next_id(self):
        try:
            query = {'_id': 'last_id'}
            update = {'$inc': {'id': 1}}
            fn = self.db.internal.find_and_modify
            row = fn(query, update, upsert=True, new=True)
        except Exception as e:
            raise DatabaseException(e)
        return row['id']
def getT(self):
        x = self.p2.x - self.p1.x
        y = self.p2.y - self.p1.y
        if (math.fabs(x) < math.pow(10,-100)):
            if(y < 0.0):
                return (-math.pi/2)
            else:
                return (math.pi/2)
        else:
            return math.atan2(y, x)