message: Add API documentation examples for tf.nest.flatten.
diff: @@ -259,6 +259,37 @@ def flatten(structure, expand_composites=False):
  Users must not modify any collections used in nest while this function is
  running.
  + Examples:
  +
  + 1. Python dict (ordered by key):
  +
  + >>> dict = { "key3": "value3", "key1": "value1", "key2": "value2" }
  + >>> tf.nest.flatten(dict)
  + ['value1', 'value2', 'value3']
  +
  + 2. For a nested python tuple:
  +
  + >>> tuple = ((1.0, 2.0), (3.0, 4.0, 5.0), (6.0))
  + >>> tf.nest.flatten(tuple)
  + [1.0, 2.0, 3.0, 4.0, 5.0, 6.0]
  +
  + 3. Numpy array (will not flatten):
  +
  + >>> array = np.array([[1, 2], [3, 4]])
  + >>> tf.nest.flatten(array)
  + [array([[1, 2],
  + [3, 4]])]
  +
  +
  + 4. `tf.Tensor` (will not flatten):
  +
  + >>> tensor = tf.constant([[1., 2., 3.], [4., 5., 6.], [7., 8., 9.]])
  + >>> tf.nest.flatten(tensor)
  + [<tf.Tensor: shape=(3, 3), dtype=float32, numpy=
  + array([[1., 2., 3.],
  + [4., 5., 6.],
  + [7., 8., 9.]], dtype=float32)>]
  +
  Args:
  structure: an arbitrarily nested structure or a scalar object. Note, numpy
  arrays are considered scalars.
  