title: Type checking on google apps script platform
body: <p>Is there a way to check againts built-in types in google apps script? 
  I don't know how to access contructors of built-in types. So I can't use instaceof operator.</p>
  
  <p>For example Profile (<a href="https://developers.google.com/apps-script/class_analytics_v3_schema_profile" rel="nofollow">https://developers.google.com/apps-script/class_analytics_v3_schema_profile</a> )</p>
  
  <pre><code>function getReportDataForProfile(profile) {
  if (profile instanceof Profile) // Profile is undefined...
  ...
  }
  </code></pre>
  
  <p>Also what is a litle confusing: When I get an instance of Profile (in variable profile)</p>
  
  <pre><code>profile.constructor // is undefined
  </code></pre>