@arr = (1 .. 20);
foreach $i ( 0 .. $#arr ) {
    if ( $i == (5 .. 10) ) {
        print "$i\n";
    }
}
# output was "0\n"

@arr = (1 .. 20);
foreach $i ( 0 .. $#arr ) {
    if ( $i == 5 .. 10 ) {
        print "$i\n";
    }
}
# output was 5-19, one integer to a line

@arr = (1 .. 20);
foreach $i ( 0 .. $#arr ) {
    if ( $i = (5 .. 10) ) {
        print "$i\n";
    }
}
# no output - '$i = (5 .. 10)' never evaluated true