var assert = require('assert');  
function demo (x,y,z) {  
  var value = x + y + z ; 
  return value;
}  
var output = demo(3,2,10);
console.log("Output : " + output);
var expected_output = 15;
console.log("Expected Output : " + expected_output);
assert( output === expected_output , 'This is not what we expected'); 