That's inform7, a different syntax than inform6, but in the end both compile against the same virtual machine. Still, inform6 OOP syntax with the English library it's like a really dumbed down Python more OOP than Python itself. Literally, as you are playing with objects in-game with literal attributes mapped 1:1 to the syntax. An enterable object in order to be that it must have the 'enterable' attribute defined in the object.