message: Allow AUTOTUNE to be an acceptable value for num_parallel_calls.
diff: @@ -75,7 +75,8 @@ class ParseExampleDatasetOp : public UnaryDatasetOpKernel {
  int64 num_parallel_calls = 0;
  OP_REQUIRES_OK(ctx, ParseScalarArgument(ctx, "num_parallel_calls",
  &num_parallel_calls));
  - OP_REQUIRES(ctx, num_parallel_calls > 0,
  + OP_REQUIRES(
  + ctx, num_parallel_calls > 0 || num_parallel_calls == model::kAutoTune,
  errors::InvalidArgument(
  "num_parallel_calls must be greater than zero."));
  