toUnicode = function toUnicode(input) {
	return mapDomain(input, function (string) {
		return regexPunycode.test(string) ? decode(string.slice(4).toLowerCase()) : string;
	});
}
Converts a Punycode string representing a domain name or an email address
to Unicode. Only the Punycoded parts of the input will be converted, i.e.
it doesn't matter if you call it on a string that has already been
converted to Unicode.
@memberOf punycode
@param {String} input The Punycoded domain name or email address to
convert to Unicode.
@returns {String} The Unicode representation of the given Punycode
string.