/**
 * Classify `input` as an IP address: `0` (no), `4` (IPv4) or `6` (IPv6).
 *
 * Matches Node's answer, including the parts that are easy to get wrong:
 * leading zeros in an IPv4 octet are rejected, an IPv6 zone id (`fe80::1%en0`)
 * is not part of the address proper, at most one `::` run is allowed, and an
 * IPv4-mapped tail (`::ffff:127.0.0.1`) must itself be a valid IPv4 address.
 */
export declare function isIP(input: string): 0 | 4 | 6;
/** Check whether `input` is a valid IPv4 address. */
export declare function isIPv4(input: string): boolean;
/** Check whether `input` is a valid IPv6 address. */
export declare function isIPv6(input: string): boolean;