my %property_hash = (
  emmisive => 'emmisiveColor',
  diffuse => 'diffuseColor',
  shineness => 'shineness',
  speculary => 'specularColor',
  transparency => 'transparency'
};

my $prop_string;
foreach my $key ( keys %property_hash ) {
  # Mark!
  $prop_string .= $key . ' ' . @{$properties{ $key }} . "\n"
    if $properties{ $key };
}
return <<"EOR";
appearance Appearance {
  material Material {
    $prop_string
  }
}
EOR

##</code><code>##

  $prop_string .= $key . ' ' . 
    ( @{$properties{ $key }} || @{$prop_def{ $key }} ) . "\n"

##</code><code>##

sub code {
   my %hash = %{ shift() };
   my $value = $hash{ 'expected' } || $const_def_hash{ 'expected' };
}

##</code><code>##

sub code {  # scalar, array ref, hash ref
   my $data = shift;
   my @array = @{ shift() };
   my %hash = %{ shift() };
}