$refhash = { UserId => 533, Something => 'foobart' }
$refarray = [ map { $_, $refhash->{$_} } keys %$refhash ];

##</code><code>##

sub header
{
    my $self = shift;
    Carp::croak('Usage: $h->header($field, ...)') unless @_;
    my(@old);
    my %seen;
    while (@_) {
	my $field = shift;
        my $op = @_ ? ($seen{lc($field)}++ ? 'PUSH' : 'SET') : 'GET';
	@old = $self->_header($field, shift, $op);
    }
    return @old if wantarray;
    return $old[0] if @old <= 1;
    join(", ", @old);
}