code: public void unassignBySlot(WorkerSlot slot) {
          List<ExecutorDetails> executors = new ArrayList<>();
          for (ExecutorDetails executor : this.executorToSlot.keySet()) {
              WorkerSlot ws = this.executorToSlot.get(executor);
              if (ws.equals(slot)) {
                  executors.add(executor);
              }
          }
  
          // remove
          for (ExecutorDetails executor : executors) {
              this.executorToSlot.remove(executor);
          }
      }
docs: Release the slot occupied by this assignment.