Failure is Nil

According to https://github.com/rakudo/rakudo/blob/master/src/core/Failure.pm6

Author: rafaelschipiura

doc/Type/Failure.pod6

@@ -4,7 +4,7 @@
 
 =SUBTITLE Delayed exception
 
-    class Failure { }
+    class Failure is Nil { }
 
 A C<Failure> is a I<soft> or I<unthrown> exception, usually generated by
 calling C<&fail>. It acts as a wrapper around an L<Exception|/type/Exception> object.
@@ -130,4 +130,4 @@ the failure as handled.
 
 =end pod
 
-# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6