How to perform simple Arithmetic Operations on leafs in Yang Module


I want to know how to perform Arithmetic Operations on Leafs and show them in CLI, in a Yang Module.
For Example, there is a list arithmetic with 2 leafs a and b.
Now I want to create a new leaf c (such that c = a+b )

list arithmetic {
tailf:callpoint xyz;
config false;
tailf:meta-data xyz{
tailf:meta-value “abc/def”;
leaf a{
description “test leaf”;
type uint64;
leaf b{
description “test leaf 2”;
type uint64;
tailf:meta-data yang-to -xyz{
tailf:meta-value “a=a1;


Here, using call point, leafs are getting data from 3rd party(D.B)

How to do the math operations.

Following… Interested to know.