/**
 * Implements fast shallow verification of hostnames. This does not perform a
 * struct check on the content of labels (classes of Unicode characters, etc.)
 * but instead check that the structure is valid (number of labels, length of
 * labels, etc.).
 *
 * If you need stricter validation, consider using an external library.
 */
/**
 * Check if a hostname string is valid. It's usually a preliminary check before
 * trying to use getDomain or anything else.
 *
 * Beware: it does not check if the TLD exists.
 */
export default function (hostname: string): boolean;