message: Explain the tf.compat module
  Fixes
diff: # See the License for the specific language governing permissions and
  # limitations under the License.
  # ==============================================================================
  -"""Functions for Python 2 vs. 3 compatibility.
  +"""Compatibility functions.
  -## Conversion routines
  -In addition to the functions below, `as_str` converts an object to a `str`.
  +The `tf.compat` module contains two sets of compatibility functions.
  +## Tensorflow 1.x and 2.x APIs
  -## Types
  -The compatibility module also provides the following types:
  +The `compat.v1` and `compat.v2` submodules provide a complete copy of both the
  +`v1` and `v2` APIs for backwards and forwards compatibility across TensorFlow
  +versions 1.x and 2.x. See the
  +[migration guide](https://www.tensorflow.org/guide/migrate) for details.
  +
  +## Utilities for writing compatible code
  +
  +Aside from the `compat.v1` and `compat.v2` submodules, `tf.compat` also contains
  +a set of helper functions for writing code that works in both:
  +
  +* TensorFlow 1.x and 2.x
  +* Python 2 and 3
  +
  +
  +## Type collections
  +
  +The compatibility module also provides the following aliases for common
  +sets of python types:
  * `bytes_or_text_types`
  * `complex_types`
  