# File lib/http/form_data/composite_io.rb, line 10
      def initialize(ios)
        @index  = 0
        @buffer = "".b
        @ios    = ios.map do |io|
          if io.is_a?(String)
            StringIO.new(io)
          elsif io.respond_to?(:read)
            io
          else
            raise ArgumentError,
              "#{io.inspect} is neither a String nor an IO object"
          end
        end
      end