def insertDomain(self, domain, indegree=0, outdegree=0):
		'''增加一个域名'''
		cur = self.conn.cursor()
		cur.execute("INSERT INTO Domains VALUES (NULL,?,?,?)", (domain, indegree, outdegree))
		# 写入到文件中
		self.conn.commit()
def get_snapshot(self, snapshot_id):
        """Returns the details of a single snapshot."""
        url = "snapshots/%s" % str(snapshot_id)
        resp, body = self.get(url)
        body = json.loads(body)
        return resp, body['snapshot']