# File lib/mongo/options/mapper.rb, line 39
      def transform(options, mappings)
        map = transform_keys_to_strings(mappings)
        opts = transform_keys_to_strings(options)
        opts.reduce({}) do |transformed, (key, value)|
          if map[key]
            transformed[map[key]] = value
          else
            transformed[key] = value
          end
          transformed
        end
      end