[tf.contrib.data] Standardize transformation functions for use with `Dataset.apply()`.
[tf.contrib.data] Standardize transformation functions for use with `Dataset.apply()`.

PiperOrigin-RevId: 169264919

rsepassi/tensor2tensor,vthorsteinsson/tensor2tensor,tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,rsepassi/tensor2tensor,waterblue13/tensor2tensor,tensorflow/tensor2tensor,rsepassi/tensor2tensor,waterblue13/tensor2tensor,tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,waterblue13/tensor2tensor,vthorsteinsson/tensor2tensor,tensorflow/tensor2tensor,tensorflow/tensor2tensor,rsepassi/tensor2tensor