import std.uuid: UUID;
var v = UUID("00112233-4455-4677-8899-aabbccddeeff");
assert(v.isUuid);
var s = "00112233-4455-4677-8899-aabbccddeeff";
assert(!s.isUuid); // strings never auto-become UUIDsvar.isUuid
bool isUuid() @property const nothrow @nogc pure @safeTrue when this value is a UUID payload (std.uuid.UUID).