code: public static function GUIDv4()
      {
          return sprintf(
              '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
              mt_rand(0, 0xffff),
              mt_rand(0, 0xffff),
              mt_rand(0, 0xffff),
              mt_rand(0, 0x0fff) | 0x4000,
              mt_rand(0, 0x3fff) | 0x8000,
              mt_rand(0, 0xffff),
              mt_rand(0, 0xffff),
              mt_rand(0, 0xffff)
          );
      }
docs: Generate v4 UUID
  
  Version 4 UUIDs are pseudo-random.
  
  @return string GUIDv4
  @static