/**
 * There's no real way to validate HTML, so this is a best guess.
 *
 * @see https://stackoverflow.com/q/1732348
 * @see https://stackoverflow.com/q/11229831
 */
export declare function isHtml(this: void, value?: any): value is string;
/**
 * Returns true if the string starts with `<html`, **ignores whitespaces and
 * casing**.
 */
export declare function isTagHtml(this: void, value: string): boolean;