message: Make stack_trace_example.py example runnable with pip.
diff: @@ -21,9 +21,16 @@ from __future__ import print_function
  import sys
  from absl import app
  -from tensorflow import enable_v2_behavior
  import tensorflow as tf # TF2
  +# Try to enable TensorFlow V2 behavior.
  +try:
  + from tensorflow import enable_v2_behavior # pylint: disable=g-import-not-at-top
  enable_v2_behavior()
  +except ImportError:
  + # `enable_v2_behavior` is not available in pip build.
  + # Ignore if the symbole isn't found. This should work in
  + # TensorFlow 2 nightly pip.
  + pass
  def suppress_exception(f):
  