Minor imports cleaning (#402)

* code cleaning

* drop unused imports

* optimize imports

pl_examples/basic_examples/lightning_module_template.py

@@ -2,16 +2,17 @@
 Example template for defining a system
 """
 import os
-from collections import OrderedDict
-import torch.nn as nn
-from torchvision.datasets import MNIST
-import torchvision.transforms as transforms
-import torch
-import torch.nn.functional as F
 from argparse import ArgumentParser
+from collections import OrderedDict
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+import torchvision.transforms as transforms
 from torch import optim
 from torch.utils.data import DataLoader
 from torch.utils.data.distributed import DistributedSampler
+from torchvision.datasets import MNIST
 
 import pytorch_lightning as pl
 from pytorch_lightning.root_module.root_module import LightningModule