This library output some strings to the console that are hardcoded in English and cannot be localized. It would be nice if these strings could be translated to other languages using for instance something like gettext.
Examples of those strings are:

• Description of default options ("Show help", "Show version", "Verbosity level") in file Command.php
• Help messages ("Comand ... version", "Usage:", "Legend...") in Command.php
• Error messages like 'Invalid value. Please try again!' in Interactor.php