*   Add `potential_scale_reduction` to
        `tf.contrib.bayesflow.mcmc_diagnostics`.
    *   Add `BatchNormalization`, `Kumaraswamy` bijectors.
    *   Deprecate `tf.contrib.learn`. Please check contrib/learn/README.md for
        instructions on how to convert existing code.
    *   `tf.contrib.data`
    *   Remove deprecated `tf.contrib.data.Dataset`, `tf.contrib.data.Iterator`,

had polished them both, I tried which was best, and ground the other
again, to see if I could make it better than that which I kept. And thus
by many Trials I learn'd the way of polishing, till I made those two
reflecting Perspectives I spake of above. For this Art of polishing will
be better learn'd by repeated Practice than by my Description. Before I
ground the Object-Metal on the Pitch, I always ground the Putty on it