code: func (iter *Iterator) ForceReseek() {
  	// Nothing to do when the iterator is associated with an immutable
  	// treap.
  	if iter.t == nil {
  		return
  	}
  
  	// Update the iterator root to the mutable treap root in case it
  	// changed.
  	iter.root = iter.t.root
  
  	// Set the seek key to the current node.  This will force the Next/Prev
  	// functions to reseek, and thus properly reconstruct the iterator, on
  	// their next call.
  	if iter.node == nil {
  		iter.seekKey = nil
  		return
  	}
  	iter.seekKey = iter.node.key
  }
docs: // ForceReseek notifies the iterator that the underlying mutable treap has been
  // updated, so the next call to Prev or Next needs to reseek in order to allow
  // the iterator to continue working properly.
  //
  // NOTE: Calling this function when the iterator is associated with an immutable
  // treap has no effect as you would expect.