/**
 * 检查 `value` 是否是以 `http` 或 `https` 开头的url
 *
 * @example
 * ```ts
 * isHttpUrl('https://www.example.com')
 * // => true
 * isHttpUrl('www.example.com')
 * // => false
 * isHttpUrl('foo/bar')
 * // => false
 * ```
 */
export declare function isHttpUrl(value: unknown): value is string;