title: Where is the hashKey variable defined in the source for the ngRepeat directive?
body: <p>Hoping to understand more about how more complex directives work, I was looking at <a href="https://github.com/angular/angular.js/blob/master/src/ng/directive/ngRepeat.js" rel="nofollow">the source of ngRepeat</a>. On <a href="https://github.com/angular/angular.js/blob/master/src/ng/directive/ngRepeat.js#L205" rel="nofollow">line 205</a>, a <code>hashFnLocals</code>variable is defined to be an object with an <code>$id</code> property. But this property is assigned a value of <code>hashKey</code>, which I don't see defined anywhere. Is it defined in another script, which it gets access to when they're concatenated during the build process?</p>