type constraint which can be used to avoid traversing a subtype
constraint hierarchy.
-B<NOTE:> You should only use this if you know what you are doing,
-all the built in types use this, so your subtypes (assuming they
+B<NOTE:> You should only use this if you know what you are doing.
+All the built in types use this, so your subtypes (assuming they
are shallow) will not likely need to use this.
=item B<< type 'Name' => where { } ... >>