/**
 * Validates one template file, or every template in a directory.
 *
 * Each valid template is confirmed on stdout; each invalid one is reported
 * on stderr with the offending node path. The command exits non-zero when
 * any template fails to load or validate.
 *
 * @param source - A template file or a directory of template files.
 */
export declare function validateCommand(source: string): Promise<void>;