*   TF Core:

    *   `tf.Graph.get_name_scope()` now always returns a string, as documented.
        Previously, when called within `name_scope("")` or `name_scope(None)`
        contexts, it returned `None`; now it returns the empty string.
    *   `tensorflow/core/ir/` contains a new MLIR-based Graph dialect that is
        isomorphic to GraphDef and will be used to replace GraphDef-based (e.g.,