code: def set_use_gpu(self, use_gpu):
      self.use_gpu = use_gpu
      if self.use_gpu and self.model != None:
          self.model.cuda()
  
imports: import torch
  import torch.nn
  from torch.autograd import Variable
  import torch.optim
  import os
  import time
  import sys
  import datetime
  import ctypes
  import json
  import numpy
  from sklearn.metrics import roc_auc_score
  import copy
  from tqdm import tqdm
label_desc: Use image node_id 4 for calling the Tester obj's underlying member method code with example usage: obj.set_use_gpu(use_gpu) without return types