/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 */
/**
 * Recursively merge the given theme configuration in-place.
 *
 * @returns If `a` and `b` are both objects (and `b` is not an Array) then
 * all keys in `b` are merged into `a` then `a` is returned.
 * Otherwise `b` is returned.
 *
 * @example
 * ```ts
 * const a = { a: "a", nested: { a: 1 } };
 * const b = { b: "b", nested: { b: 2 } };
 * const rval = deepThemeMergeInPlace(a, b);
 * expect(a).toBe(rval);
 * expect(a).toEqual({ a: "a", b: "b", nested: { a: 1, b: 2 } });
 * ```
 */
export declare function deepThemeMergeInPlace(a: unknown, b: unknown): unknown;