Almost correct.

You can motify $. but you first have to have it pointing to the correct file handle:

    print "($.)\n";    # undefined
    $. = 10;
    print "($.)\n";    # 10, but for which file handle?
    print "ENTER: ";
    ''.<STDIN>;
    print "($.)\n";    # 1, for STDIN
    $. += 10;
    print "($.)\n";    # 11, still for STDIN
    print "ENTER: ";
    ''.<STDIN>;
    print "($.)\n";    # 12, not 2 !
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                - tye