*   Added `jit_compile` as a settable property to `tf.keras.Model`.
 *   Added `synchronized` optional parameter to `layers.BatchNormalization`.

 (b) Reduction: Axes corresponding to labels appearing only in one input
     subscript but not in the output subscript are summed over prior to Tensor
     contraction.
     For example, in the equation `ab,bc->b`, the axis labels `a` and `c` are
     the reduction axis labels.

 (c) Batch Dimensions: Axes corresponding to labels appearing in each of the