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 delete_comment(self):
        "Delete the selected comment"

        if self.get_selected_item()['type'] == 'Comment':
            self.delete_item()
        else:
            self.term.flash()