/**
 * CityHash64 - Fast, non-cryptographic hash function
 *
 * Computes a 64-bit hash of the input data using Google's CityHash algorithm.
 * This is a fast, high-quality hash function suitable for hash tables and
 * other non-cryptographic uses.
 *
 * @param input - The data to hash (string or Uint8Array)
 * @returns A 64-bit hash value as a BigInt
 *
 * @example
 * ```typescript
 * import { cityHash64 } from '@anglinb/city-hash';
 *
 * // Hash a string
 * const hash1 = cityHash64("hello world");
 * console.log(hash1); // 12386028635079221413n
 *
 * // Hash binary data
 * const data = new Uint8Array([1, 2, 3, 4, 5]);
 * const hash2 = cityHash64(data);
 * ```
 */
export declare function cityHash64(input: string | Uint8Array): bigint;