Fix example of "To test if an object is a type object"

Author: zoffixznet

doc/Language/typesystem.pod6

@@ -36,16 +36,17 @@ type constraint may change in this case.
 
 =head2 Type Objects
 
-To test if an object is a type object, test for definedness and check for
-identity between the object and its C<.WHAT> pseudo-method. Note that the
-method C<.defined> can be overloaded and may provide false information.
+To test if an object is a type object, use L«C<.DEFINITE>|/routine/DEFINITE» method:
 
 =begin code :ok-test<WHAT>
     my $a = Int;
-    say so $a // $a === $a.WHAT;
+    say not $a.DEFINITE;
     # OUTPUT: «True␤»
 =end code
 
+If it returns C<True>, then the invocant is an instance. If it returns C<False>, then
+the invocant is a type object.
+
 =head3 Undefinedness
 
 Undefined objects maintain type information in Perl 6. Type objects are used to