### Bug Fixes and Other Changes

* `tf.data`
    * Add optional `synchronous` argument to `map`, to specify that the `map` should run synchronously, as opposed to be parallelizable when `options.experimental_optimization.map_parallelization=True`. This saves memory compared to setting `num_parallel_calls=1`.

auto;\n\n    // Bring the hover, focused, and \"active\" buttons to the front to overlay\n    // the borders properly\n    @include hover() {\n      z-index: 1;\n    }\n    &:focus,\n    &:active,\n    &.active {\n      z-index: 1;\n    }\n  }\n}\n\n// Optional: Group multiple button groups together for a toolbar\n.btn-toolbar {\n  display: flex;\n  flex-wrap: wrap;\n  justify-content: flex-start;\n\n  .input-group {\n    width: auto;\n  }\n}\n\n.btn-group {\n  // Prevent double borders when buttons are...

auto;\n\n    // Bring the hover, focused, and \"active\" buttons to the front to overlay\n    // the borders properly\n    @include hover() {\n      z-index: 1;\n    }\n    &:focus,\n    &:active,\n    &.active {\n      z-index: 1;\n    }\n  }\n}\n\n// Optional: Group multiple button groups together for a toolbar\n.btn-toolbar {\n  display: flex;\n  flex-wrap: wrap;\n  justify-content: flex-start;\n\n  .input-group {\n    width: auto;\n  }\n}\n\n.btn-group {\n  // Prevent double borders when buttons are...