Function empty

include/dpp/appcommand.h:756–758

* @brief Check if the value variant holds std::monostate and options vector is empty (i.e. the option wasn't supplied) * @return bool true, if value variant holds std::monostate and options vector is empty */

	 * @return bool true, if value variant holds std::monostate and options vector is empty
	 */
	bool empty() {
		return std::holds_alternative<std::monostate>(value) && options.empty();
	}

	/**
	 * @brief Get an option value by index