code: public SimpleSlot allocateSimpleSlot() throws InstanceDiedException {
  		synchronized (instanceLock) {
  			if (isDead) {
  				throw new InstanceDiedException(this);
  			}
  
  			Integer nextSlot = availableSlots.poll();
  			if (nextSlot == null) {
  				return null;
  			}
  			else {
  				SimpleSlot slot = new SimpleSlot(this, location, nextSlot, taskManagerGateway);
  				allocatedSlots.add(slot);
  				return slot;
  			}
  		}
  	}
docs: Allocates a simple slot on this TaskManager instance. This method returns {@code null}, if no slot
  is available at the moment.
  
  @return A simple slot that represents a task slot on this TaskManager instance, or null, if the
  TaskManager instance has no more slots available.
  
  @throws InstanceDiedException Thrown if the instance is no longer alive by the time the
  slot is allocated.