message: remove `global data`
diff: @@ -125,7 +125,6 @@ data_index = 0
  # Step 3: Function to generate a training batch for the skip-gram model.
  def generate_batch(batch_size, num_skips, skip_window):
  - global data
  global data_index
  assert batch_size % num_skips == 0
  assert num_skips <= 2 * skip_window
  