Show how to use Closure Compile syntax for optional properties

.js

   // Define generic object.
   // This can have any number of properties of type any.
   /**
    * @typedef {Object<string, any>} Member
    * @property {string} name The members's name.
    * @property {number=} age The members's age.
    * @property {string=} job The member's job.
    */
   /**
    * @type {Member} Jack
    */
   const Jack = {
     age: 28
   }