message: Fix adding elements to collections.deque.
diff: @@ -120,7 +120,7 @@ def generate_batch(batch_size, num_skips, skip_window):
  batch[i * num_skips + j] = buffer[skip_window]
  labels[i * num_skips + j, 0] = buffer[context_word]
  if data_index == len(data):
  - buffer[:] = data[:span]
  + buffer.extend(data[0:span])
  data_index = span
  else:
  buffer.append(data[data_index])
  