Fix F401 flake8 warning (x88 / 116).

This change is mostly autogenerated with:

    $ python -m autoflake --in-place --recursive --remove-all-unused-imports --ignore-init-module-imports examples templates transformers utils hubconf.py setup.py

I made minor changes in the generated diff.

examples/distillation/distiller.py

@@ -19,14 +19,13 @@ import math
 import os
 import time
 
-import numpy as np
 import torch
 import torch.nn as nn
 import torch.nn.functional as F
 from torch.optim import AdamW
 from torch.utils.data import BatchSampler, DataLoader, RandomSampler
 from torch.utils.data.distributed import DistributedSampler
-from tqdm import tqdm, trange
+from tqdm import tqdm
 
 import psutil
 from grouped_batch_sampler import GroupedBatchSampler, create_lengths_groups

examples/distillation/scripts/extract.py

@@ -20,7 +20,7 @@ import argparse
 
 import torch
 
-from transformers import BertForMaskedLM, GPT2LMHeadModel, RobertaForMaskedLM
+from transformers import GPT2LMHeadModel, RobertaForMaskedLM
 
 
 if __name__ == "__main__":

examples/distillation/scripts/extract_distilbert.py

@@ -20,7 +20,7 @@ import argparse
 
 import torch
 
-from transformers import BertForMaskedLM, RobertaForMaskedLM
+from transformers import BertForMaskedLM
 
 
 if __name__ == "__main__":

examples/run_bertology.py

@@ -26,8 +26,7 @@ from datetime import datetime
 
 import numpy as np
 import torch
-from torch.nn import CrossEntropyLoss, MSELoss
-from torch.utils.data import DataLoader, SequentialSampler, Subset, TensorDataset
+from torch.utils.data import DataLoader, SequentialSampler, Subset
 from torch.utils.data.distributed import DistributedSampler
 from tqdm import tqdm
 

examples/run_squad.py

@@ -26,7 +26,7 @@ import timeit
 
 import numpy as np
 import torch
-from torch.utils.data import DataLoader, RandomSampler, SequentialSampler, TensorDataset
+from torch.utils.data import DataLoader, RandomSampler, SequentialSampler
 from torch.utils.data.distributed import DistributedSampler
 from tqdm import tqdm, trange
 

examples/run_tf_ner.py

@@ -1,5 +1,4 @@
 # coding=utf-8
-import _pickle as pickle
 import collections
 import datetime
 import glob