# See the License for the specific language governing permissions and
# limitations under the License.
-import standard::kernel
+import core::kernel
redef class Int
fun next: nullable Int do if self < 20 then return self + 1 else return null
t2 = t2.next #alt2# t2 = null
end
#alt3#t2 = t2.next
+ #alt3#exit(0)
end