# File lib/zip/zipfilesystem.rb, line 227
      def open(fileName, openMode = "r", &block)
        openMode.gsub!("b", "") # ignore b option
        case openMode
        when "r" 
          @mappedZip.get_input_stream(fileName, &block)
        when "w"
          @mappedZip.get_output_stream(fileName, &block)
        else
          raise StandardError, "openmode '#{openMode} not supported" unless openMode == "r"
        end
      end