gnuplot:=System.popen("gnuplot","w");
gnuplot.writeln("unset key; plot '-'");
yellowstoneW().pump(1_000, gnuplot.writeln.fp(" "));  // " 1\n", " 2\n", ...
gnuplot.writeln("e");
gnuplot.flush();
ask("Hit return to finish"); gnuplot.close();