code: public boolean isSlotOccupied(WorkerSlot slot) {
          for (SchedulerAssignment assignment : this.assignments.values()) {
              if (assignment.isSlotOccupied(slot)) {
                  return true;
              }
          }
  
          return false;
      }
docs: Checks the specified slot is occupied.
  
  @param slot the slot be to checked.