+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Copyright 2009 Jean Privat <jean@pryen.org>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import kernel
+
+class A
+ init do end
+
+ meth work
+ do
+ if self isa B then
+ foo
+ if self isa C then
+ bar
+ end
+#alt1# bar
+ foo
+ else
+#alt2# foo
+ end
+#alt3# foo
+
+ if self isa B and self == self then
+ foo
+ end
+
+ if self isa B or self == self then
+#alt4# foo
+ end
+
+ assert self isa B
+ foo
+ end
+end
+
+class B
+special A
+ meth foo do 0.output
+ init do end
+end
+
+class C
+special B
+ meth bar do 1.output
+ init do end
+end
+
+var a: A
+a = new C
+#alt5#a = new B
+#alt6#a = new A
+a.work