Select Code to Download

my $i= 0;
$str =~ s/(...)/ 3 == ++$i ? 'fish' : $1 /ge;

my $i = 3;
0 while $str =~ /fsih/gi && --$i;
substr( $str, $-[0], $+[0]-$-[0], 'fish' )   if  ! $i;