sub doSomethingX {
    my $string = shift;
    $string =~ tr/foo/X/;
    return doSomething($string);
}

sub doSomethingY {
    my $string = shift;
    $string =~ tr/foo/Y/;
    return doSomething($string);
}

sub doSomething {
    my ($var) = shift;
    print $var;
}