function greet(name) {
  if (name) {
    console.log('Hello, ' + name + '!');
  } else {
    console.log('Hello there!');
  }
}

function calculateSum(a, b) {
  return a + b;
}

var num1 = 5;
var num2 = 10;
var sum = calculateSum(num1, num2);

console.log('The sum of ' + num1 + ' and ' + num2 + ' is: ' + sum);