*   Improved support for NumPy style basic slicing including non-1 strides,
    ellipses, newaxis, and negative indices. For example complicated expressions
    like `foo[1, 2:4, tf.newaxis, ..., :-3:-1, :]` are now supported. In
    addition we have preliminary (non-broadcasting) support for sliced
    assignment to variables. In particular one can write
    `var[1:3].assign([1,11,111])`.