$nest->nest('newlevel', attr1 => 1,
                        attr2 => 2,
                        attr3 => 3);

##</code><code>##

printf "%d", [3.4];

##</code><code>##

sub nest {
    my $tagname = $_[0];
    my $attributes = @_ == 2 ? $_[1] : [@_[1 .. $#_]];
    ...
}