(PHP 5 >= 5.4.0)
CallbackFilterIterator::__construct — Create a filtered iterator from another iterator
   Creates a filtered iterator using the callback to 
   determine which items are accepted or rejected.
  
iterator
    The iterator to be filtered.
callback
    
      The callback, which should return TRUE to accept the current item
      or FALSE otherwise.
      See Examples.
     
May be any valid callable value.
没有返回值。