dispatches the best kernel implementation based on CPU vector
        architecture. To disable them, build with
        `--define=tensorflow_mkldnn_contraction_kernel=0`.
    *   `tf.linspace(start, stop, num)` now always uses "stop" as last value
        (for num > 1)
    *   Added top-k to precision and recall to keras metrics.
    *   Add a ragged size op and register it to the op dispatcher