		public final Void call() throws Exception {
			if (isDone()) throw new IllegalStateException("This task is already done!");
			$IN $a = $src.readNow();
			if ($a == null) return null;
			$OUT $b = run($a);
			if ($b == null) return null;
			$sink.write($b);
			return null;
		}

		public final Void call() throws Exception {
			if (isDone()) return null;
			$IN $a = $src.readNow();
			if ($a == null) return null;
			$OUT $b = run($a);
			if ($b == null) return null;
			$sink.write($b);
			return null;
		}
