import { LitElement } from 'lit';
export declare const internals: unique symbol;
export declare const updateInternals: unique symbol;
export declare const replaceStates: unique symbol;
export declare class InternalsAttachedInterface {
    [internals]: ElementInternals;
    [updateInternals]?(): void;
    [replaceStates](del: Array<string>, add: Array<string>): void;
}
export declare const InternalsAttached: <T extends Constructor<LitElement>>(superClass: T) => Constructor<InternalsAttachedInterface> & T;