Where is IonicApp located?

I am trying to import IonicApp. My code looks like this:

 constructor(app:IonicApp)

It says it cannot find IonicApp, where is it located?

Do you have the import?

Import {IonicApp} from 'ionic-angular'

Ahhhh it was something wrong with my IDE. It kept saying it didn’t exist there. I have cleared the cache of the IDE and now it works. Thanks.