code: public List<WorkerSlot> getAvailableSlots(SupervisorDetails supervisor) {
          Set<Integer> ports = this.getAvailablePorts(supervisor);
          List<WorkerSlot> slots = new ArrayList<>(ports.size());
  
          for (Integer port : ports) {
              slots.add(new WorkerSlot(supervisor.getId(), port));
          }
  
          return slots;
      }
docs: Return all the available slots on this supervisor.