def save(self, doc):
        if doc.id:
            return self.update(doc)
        else:
            return self.insert(doc)
def get_leafs(self):
		if self.lchild == None and self.rchild == None:
			return [self.leaf]
		else:
			return self.lchild.get_leafs()+self.rchild.get_leafs()