add assignment b

u07-2/README.md

@@ -12,13 +12,22 @@ public class SimpleExecutorCompletionService<ResultType> {
 	// Fetch result of some finished task if available (else null):
 	public Future<ResultType> poll() { … }
 }
-
 ```
 
 Use class `SimpleExecutorCompletionServiceTester` oin the file server to test your class. If your
 implementation is correct, the numbers printed with "… received result" should appear in mostly[^1]
 ascending order. Method `Future.isDone()` could be helpful for your implementation.
 
+b) Add the following method to your class:
+```java
+	// Fetch result of some finished task (blocks until some has finished):
+	public Future<ResultType> take() throws InterruptedExecution { … }
+```
+
+Note that you have to change the submit method from (a), too, so that when a task finishes, the
+threads waiting in take for a task to finish are notified. Use class
+`SimpleExecutorCompletionServiceTester_with_take` on the server to test your class.
+
 [^1]: This order is not really guaranteed: While the "internal" length of each task would indeed produce this order,
 the total execution time of a task may be longer due to external delays by the thread pool (e.g. how long it takes
 to start a submitted task) and by other threads (e.g. preemption).