use strict;
use warnings;

$|=1;
open(STDOUT, '+<') or die "open: $!";

print STDOUT "11111111111111111111111111111111\n" or die "print 1: $!";

for (0..31){
  seek(STDOUT, $_, 0) or die "seek: $!";
  print STDOUT '0' or die "print 0: $!";
  sleep(1);
}
close(STDOUT);

##</code><code>##

open(STDOUT, '+<', "&STDOUT") or die "open: $!";