message: Convert to doctest format.
  Ran:
  `git rebase -i --onto master r2.0 assert-shapes`
  From
diff: @@ -1592,14 +1592,27 @@ def assert_shapes_v2(shapes, data=None, summarize=None, message=None,
  Example:
  - ```python
  - tf.assert_shapes([
  - (x, ('N', 'Q')),
  - (y, ('N', 'D')),
  - (param, ('Q',)),
  - (scalar, ()),
  - ])
  - ```
  + >>> n = 10
  + >>> q = 3
  + >>> d = 7
  + >>> x = tf.zeros([n,q])
  + >>> y = tf.ones([n,d])
  + >>> param = tf.Variable([1.0, 2.0, 3.0])
  + >>> scalar = 1.0
  + >>> tf.debugging.assert_shapes([
  + ... (x, ('N', 'Q')),
  + ... (y, ('N', 'D')),
  + ... (param, ('Q',)),
  + ... (scalar, ()),
  + ... ])
  +
  + >>> tf.debugging.assert_shapes([
  + ... (x, ('N', 'D')),
  + ... (y, ('N', 'D'))
  + ... ])
  + Traceback (most recent call last):
  + ...
  + ValueError: ...
  If `x`, `y`, `param` or `scalar` does not have a shape that satisfies
  all specified constraints, `message`, as well as the first `summarize` entries
  