/** @module read-file-string
 */
declare module "read-file-string" {
    /**
     * @function
     * @param {string} file Path to a file
     * @returns {Promise<string|null>} File contents in UTF-8 or null if file could not be read
     * @example
     * import readFileString from "read-file-string"
     * const result = await readFileString("readme.md")
     * result === "## Hewwo OwO"
     */
    export default function(file: string): Promise<string | null>;
    /**
     * @function
     * @param {string} file Path to a file
     * @returns {string|null} File contents in UTF-8 or null if file could not be read
     * @example
     * import {readFileStringSync} from "read-file-string"
     * const result = readFileStringSync("readme.md")
     * result === "## Hewwo OwO"
     */
    export function readFileStringSync(file: string): string | null;
}