allow example to compile

Author: coke

doc/Language/py-nutshell.pod6

@@ -529,6 +529,7 @@ print e.name
 
 Perl 6
 
+=for code :preamble<class Dog {}>
     my $d = Dog.new(:name<Fido>); # or: Dog.new(name => 'Fido')
     my $e = Dog.new(:name<Buddy>);
     say $d.name;