/**
 * Returns an object with rule as a key and its config as a value,
 * if a given rule belongs to an installed ESLint plugin.
 *
 * Otherwise, returns an empty object.
 *
 * @since v0.21.0
 */
export declare function optionalRule(rule: string, config: unknown): Record<string, unknown>;
/**
 * Returns true if a given ESLint plugin exists.
 *
 * @since v0.21.0
 */
export declare function hasEslintPlugin(plugin: string): boolean;