text: /*
   You can see in this simple example that an argument passed into a function can be a function itself, 
   and this is what makes callbacks possible in JavaScript.
  */
  
  function mySandwich(param1, param2, callback) {
      console.log('\nStarted eating my sandwich.\n');
  
      if (param1) {
          console.log(`It has: ${param1}\n`);
      }
  
      if (param2) {
          console.log(`It has: ${param2}\n`);
      }
      
      if (callback && typeof (callback) === "function") {
          callback();
      }
  }
  
  mySandwich('ham', 'cheese', function () {
      console.log('Finished eating my ham sandwich.');
  });
  
  // using arrows function
  mySandwich('chicken', 'cheese', () => {
      console.log('Finished eating my chicken sandwich.');
  });