*   DType is no longer convertible to an int. Use `dtype.as_datatype_enum`
        instead of `int(dtype)` to get the same result.
    *   Support both binary and -1/1 label input in v2 hinge and squared hinge
        losses.
    *   Added `LinearOperator.adjoint` and `LinearOperator.H` (alias).
    *   Expose CriticalSection in core as `tf.CriticalSection`.
    *   Enhanced graphviz output.