u can see, the <code>PhoneNumber</code> type is defined inside <code>Person</code>. You can also define <code>enum</code> types if you want one of your fields to have one of a predefined list of values – here you want to specify that a phone number can be one of <code>MOBILE</code>, <code>HOME</code>, or <code>WORK</code>.</p>
<p>The “ = 1”, “ = 2” markers on each element identify the unique “tag” that field uses in the binary encoding. Tag numbers 1-15 require one less byte to encode than hig