/**
 * Generates an authentication string based on the provided credentials.
 *
 * @param {Object} data - An object containing the authentication credentials.
 * @param {string} [data.username] - The username to use for authentication.
 * @param {string} [data.password] - The password to use for authentication.
 * @param {string} [data.token] - The token to use for authentication.
 * @returns {string} The authentication string.
 */
export declare const getAuthString: (data: {
    username?: string;
    password?: string;
    token?: string;
}) => string;