# File lib/rack/multipart/generator.rb, line 12
      def dump
        return nil if @first && !multipart?
        return flattened_params if !@first

        flattened_params.map do |name, file|
          if file.respond_to?(:original_filename)
            ::File.open(file.path, "rb") do |f|
              f.set_encoding(Encoding::BINARY) if f.respond_to?(:set_encoding)
              content_for_tempfile(f, file, name)
            end
          else
            content_for_other(file, name)
          end
        end.join + "--#{MULTIPART_BOUNDARY}--\r"
      end