fix pickles

examples/run_classifier.py

@@ -40,6 +40,12 @@ from pytorch_pretrained_bert.optimization import BertAdam, WarmupLinearSchedule
 
 from run_classifier_dataset_utils import processors, output_modes, convert_examples_to_features, compute_metrics
 
+if sys.version_info[0] == 2:
+    import cPickle as pickle
+else:
+    import pickle
+
+
 logger = logging.getLogger(__name__)