/**
 * Creates an array of unique values, in order, from all given arrays.
 *
 * @param arrays - The arrays to inspect
 * @returns The new array of combined unique values
 *
 * @example
 * ```ts
 * union([2], [1, 2]);
 * // => [2, 1]
 * ```
 */
export declare function union<T>(...arrays: T[][]): T[];
/**
 * Creates an array of unique values, in order, from all given arrays
 * using deep equality comparison.
 *
 * @param arrays - The arrays to inspect
 * @returns The new array of combined unique values
 *
 * @example
 * ```ts
 * unionDeep([{ 'x': 1 }], [{ 'x': 1 }, { 'x': 2 }]);
 * // => [{ 'x': 1 }, { 'x': 2 }]
 * ```
 */
export declare function unionDeep<T>(...arrays: T[][]): T[];
/**
 * Creates an array of unique values, in order, from all given arrays
 * using a custom iteratee function.
 *
 * @param arrays - The arrays to inspect with the last argument being a function or property name
 * @returns The new array of combined unique values
 *
 * @example
 * ```ts
 * unionBy([2.1], [1.2, 2.3], Math.floor);
 * // => [2.1, 1.2]
 *
 * unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
 * // => [{ 'x': 1 }, { 'x': 2 }]
 * ```
 */
export declare function unionBy<T, K = T>(...arrays: [...T[][], ((value: T) => K) | keyof T]): T[];