/**
 * Infer the estimated reading time from a document as file metadata.
 *
 * The reading time is inferred not just on words per minute, but also takes
 * readability into account.
 * The result is stored on `file.data.meta.readingTime`.
 *
 * @param {Readonly<Options> | null | undefined} [options]
 *   Configuration (optional).
 * @returns
 *   Transform.
 */
export default function rehypeInferReadingTimeMeta(options?: Readonly<Options> | null | undefined): (tree: Root, file: VFile) => undefined;
export type Root = import('hast').Root;
export type VFile = import('vfile').VFile;
/**
 * Configuration.
 */
export type Options = {
    /**
     * Target age group (default: `[16, 18]`); this is the age your target
     * audience was still in school; so, set it to `18` if you expect all readers
     * to have finished high school, `21` if you expect your readers to be
     * college graduates, etc; can be two numbers in an array to get two
     * estimates.
     */
    age?: [number, number] | [number] | number | null | undefined;
    /**
     * CSS selector to body of content (optional, example: `'main'`); useful to
     * exclude other things, such as the head, ads, styles, scripts, and other
     * random stuff, by focussing all strategies in one element.
     */
    mainSelector?: string | null | undefined;
};