title: Cannot manually load kears imbd dataset
body: <p>following this instruction: <a href="https://stackoverflow.com/questions/40690203/the-alternative-to-from-keras-datasets-import-mnist/51632839">the alternative to from keras.datasets import mnist</a></p>
  
  <p>I am able to load the mnist dataset, with the following lines:</p>
  
  <pre><code>f = gzip.open('C:/.../Datasets/mnist.pkl.gz', 'rb')
  if sys.version_info &lt; (3,):
      data = pickle.load(f)
  else:
      data = pickle.load(f, encoding='bytes')
  f.close()
  
  (x_train, y_train),(x_test, y_test) = data
  </code></pre>
  
  <p>But when I try the same for the IMDB dataset, which i saved as tar.gz file, which the following command:</p>
  
  <pre><code>imdb = gzip.open('C:/.../Datasets/aclImdb_v1.tar.gz', 'rb')
  if sys.version_info &lt; (3,):
      data = pickle.load(imdb)
  else:
      data = pickle.load(imdb, encoding='bytes')
  imdb.close()
  </code></pre>
  
  <p>I get the error:</p>
  
  <pre><code>UnpicklingError: unpickling stack underflow
  </code></pre>
  
  <p>I am not allowed to load it with: </p>
  
  <pre><code>imdb = keras.datasets.imdb
  
  (train_data, train_labels), (test_data, test_labels) = imdb.load_data(num_words=10000)
  </code></pre>
  
  <p>because I am behind a proxy.</p>