Example Room container for martianman

room.py

class Room(object):
    def __init__(self):
        self._container = set()
    
    def __contains__(self, item):
        return self._container.__contains__(item)

    def add(self, item):
        self._container.add(item)
        item.room.remove(item)
        item.room = self

    def remove(self, item):
        if item in self:
            self._container.dispose(item)
            item.room = None

    def contents(self):
        return list(self._container)