title: Get the key of an item on a Collection object
body: <p>The environment is that the members I'm pushing into the Collection are nameless, un-identifiable (to avoid bad abstractions, and please, don't freak out: members are actually other Collection instances).
  In order to be able to make fast searches, I'm creating a meaningfull hash name for each new member, and provide it as the Key string, on the Add method of the "topmost" Collection.</p>
  
  <p>When I have a key to seach with, everything's dandy...
  Problem is I'd like to iterate the members of the collection and get the Key that was provided on Add (the generated Hash, that unfortunetely is not possible to reverse-Hash).</p>
  
  <p>I'm moving on by defining that the first member of the inserted sub-collection instance is a string, containing the mentioned hash, but if anyone cracks this, I'll be much obliged.</p>