def __init__(self, name, host='127.0.0.1', port=27017):
        self.name = name
        self.host = host
        self.port = port
def distance(self, pt):
        self.pt = pt
        x = self.x - self.pt.x
        y = self.y - self.pt.y
        return math.sqrt(x * x + y * y)