message: updated zip example
diff: @@ -566,27 +566,25 @@ class DatasetV2(object):
  For example:
  ```python
  - # NOTE: The following examples use `{ ... }` to represent the
  - # contents of a dataset.
  - a = { 1, 2, 3 }
  - b = { 4, 5, 6 }
  - c = { (7, 8), (9, 10), (11, 12) }
  - d = { 13, 14 }
  + a = Dataset.range(1, 4) # [ 1, 2, 3 ]
  + b = Dataset.range(4, 7) # [ 4, 5, 6 ]
  + c = Dataset.from_tensor_slices(tf.reshape(tf.range(7,13), (3,2))) # [ [7, 8], [9, 10], [11, 12] ]
  + d = Dataset.range(13, 15) # [ 13, 14 ]
  # The nested structure of the `datasets` argument determines the
  # structure of elements in the resulting dataset.
  - Dataset.zip((a, b)) == { (1, 4), (2, 5), (3, 6) }
  - Dataset.zip((b, a)) == { (4, 1), (5, 2), (6, 3) }
  + Dataset.zip((a, b)) # ==> [ (1, 4), (2, 5), (3, 6) ]
  + Dataset.zip((b, a)) # ==> [ (4, 1), (5, 2), (6, 3) ]
  # The `datasets` argument may contain an arbitrary number of
  # datasets.
  - Dataset.zip((a, b, c)) == { (1, 4, (7, 8)),
  - (2, 5, (9, 10)),
  - (3, 6, (11, 12)) }
  + Dataset.zip((a, b, c)) # ==> [ (1, 4, [7, 8]),
  + # (2, 5, [9, 10]),
  + # (3, 6, [11, 12]) ]
  # The number of elements in the resulting dataset is the same as
  # the size of the smallest dataset in `datasets`.
  - Dataset.zip((a, d)) == { (1, 13), (2, 14) }
  + Dataset.zip((a, d)) # ==> [ (1, 13), (2, 14) ]
  ```
  Args:
  