sub uniq
{
    local $_;
    my %seen;
    return grep { !$seen{$_}++ } @_;
}

print uniq 0,0,1,2;         # good: prints 0,1,2
print sort uniq 0,0,1,2;    # bad:  prints 0,0,1,2

##</code><code>##

print sort uniq(0,0,1,2);


##</code><code>##

print sort grep {1} uniq 0,0,1,2;