title: addEntriesFromDictionary: a true copy method?
body: <p>I am trying to understand exactly what is going on with this method, as noted in the Apple docs:</p>
  
  <p><a href="http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/Reference/Reference.html" rel="nofollow">http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/Reference/Reference.html</a></p>
  
  <p>If I create an <code>NSMutableDicationary</code> and use <code>addEntriesFromDictionary:</code> to fill it, can I do anything I want to this mutable dictionary without affecting the original immutable dictionary from where these items came?</p>