text: 'use strict';
  
  const greet = require('./lib/greet.js');
  const math = require('./lib/arithmetic.js');
  console.log(greet('JOHN')); // hello, JOHN
  console.log(greet(12)); // null
  console.log(math.add([1,3,10])); // 14
  console.log(math.subtract([1,3,10])); // -12
  console.log(math.multiply([5,5,10])); // 250
  console.log(math.divide([10,2,5])); // 5
  console.log(math.divide([10,0])); // Cannot divide by zero
  