# File lib/bson/ordered_hash.rb, line 155
      def reject!
        return to_enum(:reject!) unless block_given?
        raise "can't modify frozen BSON::OrderedHash" if frozen?
        keys = @ordered_keys.dup
        @ordered_keys.each do |k|
          if yield k, self[k]
            keys.delete(k)
          end
        end
        keys == @ordered_keys ? nil : @ordered_keys = keys
      end