/**
 * Converts any value to string.
 *
 * @param {*} value The value to stringify.
 * @returns {string}
 */
export declare function stringify(value: unknown): string;
/**
 * Checks if given variable is defined.
 *
 * @param {*} variable Variable to check.
 * @returns {boolean}
 */
export declare function isDefined(variable: unknown): boolean;
/**
 * Checks if given variable is undefined.
 *
 * @param {*} variable Variable to check.
 * @returns {boolean}
 */
export declare function isUndefined(variable: unknown): boolean;
/**
 * Check if given variable is null, empty string or undefined.
 *
 * @param {*} variable Variable to check.
 * @returns {boolean}
 */
export declare function isEmpty(variable: unknown): boolean;
/**
 * Check if given variable is a regular expression.
 *
 * @param {*} variable Variable to check.
 * @returns {boolean}
 */
export declare function isRegExp(variable: unknown): boolean;
export declare function _injectProductInfo({ className, key, element, releaseDate }: {
    className?: string;
    key?: string;
    element?: HTMLElement;
    releaseDate?: string;
}): HTMLElement | null;