def save(self, doc):
        if doc.id:
            return self.update(doc)
        else:
            return self.insert(doc)
def paint(self, c):
		self.leaf.paint(c)
		if self.lchild != None:
			self.lchild.paint(c)
		if self.rchild != None:
			self.rchild.paint(c)