* returns true and Argument is set as used one. If there was an error
* during conversion, method returns false and can be used to check
* against next value.
*/
virtual bool understand(const std::string & argv) {
* returns true and Argument is set as used one. If there was an error
* during conversion, method returns false and can be used to check
* against next value.
*/
virtual bool understand(const std::string & argv) {