import { LitElement } from '@rxdi/lit-html';
/**
 * @customElement r-let
 */
export declare class LetOperator extends LitElement {
    data: any[];
    item: (v: any) => import("lit-html").TemplateResult<1>;
    OnUpdateFirst(): void;
    private normalizeArray;
    private isObservable;
    private isFunction;
}