export interface EngineInfo {
    author: string | undefined;
    description: string | undefined;
    image: string | undefined;
    keywords: string[] | undefined;
    lang: string | undefined;
    length: number;
    size: {
        height: number;
        width: number;
    };
    theme: string | undefined;
    title: string | undefined;
    url: string | undefined;
}
export declare const engineInfo: unique symbol;
export default function infoPlugin(md: any): void;
