public function seconds($seconds) {

		if(false === ('-' . intval($seconds) == '-' . $seconds)) {
   			return trigger_error(sprintf('Argument 1 passed to %s() must be of the type integer, "%s" given', __METHOD__, gettype($seconds)), E_USER_ERROR);
   		}

		$this -> seconds = $seconds;

		return $this;
	}