ription" class="description"><p>Deep merge of options objects
Whenever a property is an object on both options objects
the two properties will be merged using mergeOptions.</p>
<pre class="prettyprint source lang-js"><code>    Parent.prototype.options_ = {
      optionSet: {
        'childOne': { 'foo': 'bar', 'asdf': 'fdsa' },
        'childTwo': {},
        'childThree': {}
      }
    }
    newOptions = {
      optionSet: {
        'childOne': { 'foo': 'baz', 'abc': '123' }
        'childTwo': null,
    