message: Worry about boolean conversions in get_argspec_for_partial
  This does not solve all tf.function-and-partial bugs but makes debugging simpler.
diff: @@ -216,7 +216,8 @@ def _get_argspec_for_partial(obj):
  # Checks if all arguments have default value set after first one.
  invalid_default_values = [
  - args[i] for i, j in enumerate(all_defaults) if not j and i > first_default
  + args[i] for i, j in enumerate(all_defaults)
  + if j is None and i > first_default
  ]
  if invalid_default_values:
  