/**
 * Make a private environment variable public, so that it can be accessed in the
 * browser.
 *
 * Usage:
 * ```ts
 * // Make a single variable public.
 * makeEnvPublic('FOO');
 *
 * // Make multiple variables public.
 * makeEnvPublic(['FOO', 'BAR', 'BAZ']);
 * ```
 */
export declare function makeEnvPublic(key: string | string[]): void;