export default class Helper {
    static sleep(seconds: number): Promise<void>;
    static now(days: number): Date;
    static formUrlEncoded(x: unknown): string;
    static jsonToForm(body: unknown): string;
    static random(len?: number): string;
    static random48(): string;
    /**
     * Before posting data to api. we will try to remove undefined/null properties
     * because
     * @param data any
     */
    static removeInvalidFields(data: any): any;
}