def getCliInstance():
	global _dbcli
	if not _dbcli:
		_dbcli = DatabaseHelper()
	return _dbcli
def paint(self, c):
		self.leaf.paint(c)
		if self.lchild != None:
			self.lchild.paint(c)
		if self.rchild != None:
			self.rchild.paint(c)