code: def _before_train(self):
      global args
      self.val_ds = get_data(args.data, isTrain=False)
      self.val_ds.reset_state()
  
imports: import argparse
  import glob
  import os
  import tensorflow
  from six.moves import range
  from tensorpack import *
  from tensorpack.tfutils.scope_utils import auto_reuse_variable_scope
  from tensorpack.tfutils.summary import add_moving_summary
  from GAN import GANModelDesc, GANTrainer
label_desc: Use image node_id 2 for calling the VisualizeTestSet obj's underlying member method code with example usage: obj._before_train() without return types