title: +[NSString stringWithString:] -- what's the point?
body: <p>As <code>NSString</code> strings are immutable, what is the value of the <code>stringWithString:</code> class method?</p>
  
  <p>I get the utility when used with <code>NSMutableString</code>, I just didn't see the utility with the <code>NSString</code> class.</p>