text: var data = {};
  
  Object.defineProperty(data, 'type', {
    value: 'primary',
    enumerable: true
  });
  
  console.log(data.type); // primary
  data.type = 'secondary'; 
  console.log(data.type); // nope, still primary
  
  Object.defineProperty(data, 'id', {
    value: 1,
    writable: true
  });
  
  console.log(data.id); // 1
  data.id=300; 
  console.log(data.id); // 300
  
  for (prop in data) {
    console.log(prop); // only type displays
  }
  
  