CatInterpreter constructor
_catInterpreter is a singleton instance of CatInterpreter that is created
when the first call to CatInterpreter() is made
Implementation
factory CatInterpreter() => _catInterpreter;
_catInterpreter is a singleton instance of CatInterpreter that is created
when the first call to CatInterpreter() is made
factory CatInterpreter() => _catInterpreter;