code: func (iter *dbCacheIterator) Next() bool {
  	// Nothing to return if cursor is exhausted.
  	if iter.currentIter == nil {
  		return false
  	}
  
  	// Move the current iterator to the next entry and choose the iterator
  	// that is both valid and has the smaller key.
  	iter.currentIter.Next()
  	return iter.chooseIterator(true)
  }
docs: // Next moves the iterator one key/value pair forward and returns whether or not
  // the pair exists.
  //
  // This is part of the leveldb iterator.Iterator interface implementation.