foreach $products (@{$file->{product}})    {
    print "Widget: " . $products->{title} ." \n";
    print "Rating: " . $products->{rating} . "\n";
    print "  Cost: " . $products->{cost} . "\n";
    print "Colors: " . join(', ', @{$products->{color}})."\n\n";
}

##</code><code>##

<shelf>
    <product>
        <title>widget3</title>
        <cost>0.50</cost>
        <rating>S</rating>
        <color>white</color>
    </product>
</shelf>

##</code><code>##

<shelf>
    <product>
        <title>widget1</title>
        <cost>0.10</cost>
        <rating>B</rating>
        <color>red</color>
        <color>blue</color>
        <color>green</color>
    </product>

    <product>
        <title>widget2</title>
        <cost>0.25</cost>
        <rating>S</rating>
        <color>pink</color>
        <color>gray</color>
        <color>orange</color>
    </product>
</shelf>

##</code><code>##

sub list {
   if (defined(ref($_[0])) && ref($_[0]) eq 'ARRAY') {
      return @{ $_[0] };
   } else {
      return $_[0];
   }
}

foreach $products (list($file->{product}))    {
    print "Widget: " . $products->{title} ." \n";
    print "Rating: " . $products->{rating} . "\n";
    print "  Cost: " . $products->{cost} . "\n";
    print "Colors: " . join(', ', list($products->{color}))."\n\n";
}