my $argN="default";
$argN=shift if @_;

##</code><code>##

&foo (1,2,3);

sub foo {
    my @defaults= qw (foo bar baz quux quuz boo);
    for (1.. @_) {shift @defaults};
    @_= (@_, @defaults);
    ($a1, $a2, $a3, $a4, $a5, $a6) = @_;    
    print join "\n",$a1, $a2, $a3, $a4, $a5, $a6;
}