sub greet {
      my ($name, $age) = @_;

      # required param
      $name or die "must supply name" ;
      # optional param, defaults to 25
      $age  ||= 25;

      print "Hello, there $name. How does it feel to be $age?\n";
    }
    
##</code><code>##

    use Params::Validate qw(:all);
    sub greet {
      my %p = validate(@_, {
        name => 1, # required
        age  => { default => 25 }
      })
    }

    print "Hello, there $name. How does it feel to be $age?\n";

    
##</code><code>##

 sub HTML::Element::iter2 {

  my $tree = shift;

  my %p = validate(
    @_, {
      # the container look-down. defaults to ['_tag' => 'dl']
      wrapper_ld    => { default => ['_tag' => 'dl'] },

      # the data to fill the container with. mandatory
      wrapper_data  => 1,

      # the routine to preprocess the HTML::Element container
      # by default no preprocessing is done
      wrapper_proc  => { default => undef },

      # the routine to find the "templated" sub-elements of container
      # by default returns an arrayref consisting on the dt and dd tags
      item_ld       => { default => sub { 
			   my $tree = shift;
			   [
			     $tree->look_down('_tag' => 'dt'),
			     $tree->look_down('_tag' => 'dd')
			    ];
			 }
			},

      # the routine to return a row of data from wrapper_data
      # the default routine simply shifts off a row. you might
      # replace this with $wrapper_data->next in some cases
      item_data     => { default => sub { my ($wrapper_data) = @_;
					  shift(@{$wrapper_data}) ;
					}},
      # the routine to take the row of data and populate the item tags
      # the default routine takes a two-element array and fills the 
      # dt and dd tags
      item_proc     => {
	default => sub {
	  my ($item_elems, $item_data, $row_count) = @_;
	  $item_elems->[$_]->replace_content($item_data->[$_]) for (0,1) ;
	  $item_elems;
	}},
      
      # the routine to place the accumulated item rows back in the the
      # HTML::Tree. By default removes the two sample rows (dt and dd)
      # and replaces them with all the item rows
      splice        => { default => sub {
			   my ($container, @item_elems) = @_;
			   $container->splice_content(0, 2, @item_elems);
			 }
			},
      # output debug info? by default, no
      debug => {default => 0}