# File lib/zip/zipfilesystem.rb, line 233
      def open(fileName, openMode = "r", permissionInt = 0644, &block)
        openMode.gsub!("b", "") # ignore b option
        case openMode
          when "r"
            @mappedZip.get_input_stream(fileName, &block)
          when "w"
            @mappedZip.get_output_stream(fileName, permissionInt, &block)
          else
            raise StandardError, "openmode '#{openMode} not supported" unless openMode == "r"
        end
      end