hints from pep8speaks

Author: ybrovman

pytorch_lightning/trainer/data_loading.py

@@ -187,7 +187,7 @@ def _reset_eval_dataloader(self, model: LightningModule,
             dataloaders = [dataloaders]
 
         # add samplers
-        dataloaders = [self.auto_add_sampler(dl, train=False) for dl in dataloaders if dl != None]
+        dataloaders = [self.auto_add_sampler(dl, train=False) for dl in dataloaders if dl is not None]
 
         num_batches = 0