message: fix code formatting (spacing+example)
diff: @@ -566,10 +566,10 @@ class DatasetV2(object):
  For example:
  ```python
  - a = Dataset.range(1, 4) # [ 1, 2, 3 ]
  - b = Dataset.range(4, 7) # [ 4, 5, 6 ]
  - c = Dataset.from_tensor_slices([[7, 8], [9, 10], [11, 12]])
  - d = Dataset.range(13, 15) # [ 13, 14 ]
  + a = Dataset.range(1, 4) # ==> [ 1, 2, 3 ]
  + b = Dataset.range(4, 7) # ==> [ 4, 5, 6 ]
  + c = Dataset.range(7, 13).batch(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.
  @@ -599,12 +599,12 @@ class DatasetV2(object):
  """Creates a `Dataset` by concatenating given dataset with this dataset.
  ```python
  - a = Dataset.range(1, 4) # [ 1, 2, 3 ]
  - b = Dataset.range(4, 8) # [ 4, 5, 6, 7 ]
  + a = Dataset.range(1, 4) # ==> [ 1, 2, 3 ]
  + b = Dataset.range(4, 8) # ==> [ 4, 5, 6, 7 ]
  # Input dataset and dataset to be concatenated should have same
  # nested structures and output types.
  - # c = Dataset.from_tensor_slices([[8, 9], [10, 11], [12, 13]])
  + # c = Dataset.range(8, 14).batch(2) # ==> [ [8, 9], [10, 11], [12, 13] ]
  # d = Dataset.from_tensor_slices([14.0, 15.0, 16.0])
  # a.concatenate(c) and a.concatenate(d) would result in error.
  @@ -932,7 +932,7 @@ class DatasetV2(object):
  For example:
  ```python
  - a = Dataset.range(1, 6) # [ 1, 2, 3, 4, 5 ]
  + a = Dataset.range(1, 6) # ==> [ 1, 2, 3, 4, 5 ]
  a.map(lambda x: x + 1) # ==> [ 2, 3, 4, 5, 6 ]
  ```
  @@ -1082,7 +1082,7 @@ class DatasetV2(object):
  For example:
  ```python
  - a = Dataset.range(1, 6) # [ 1, 2, 3, 4, 5 ]
  + a = Dataset.range(1, 6) # ==> [ 1, 2, 3, 4, 5 ]
  # NOTE: New lines indicate "block" boundaries.
  a.interleave(lambda x: Dataset.from_tensors(x).repeat(6),
  @@ -1133,13 +1133,13 @@ class DatasetV2(object):
  ```python
  d = tf.data.Dataset.from_tensor_slices([1, 2, 3])
  - d = d.filter(lambda x: x < 3) # [1, 2]
  + d = d.filter(lambda x: x < 3) # ==> [1, 2]
  # `tf.math.equal(x, y)` is required for equality comparison
  def filter_fn(x):
  return tf.math.equal(x, 1)
  - d = d.filter(filter_fn) # [1]
  + d = d.filter(filter_fn) # ==> [1]
  ```
  Args:
  