def list_things_at(self, location, tclass=Thing):
        "Return all things exactly at a given location."
        return [thing for thing in self.things
                if thing.location == location and isinstance(thing, tclass)]
def list_things_at(self, location, tclass=Thing):
        "Return all things exactly at a given location."
        return [thing for thing in self.things
                if thing.location == location and isinstance(thing, tclass)]
def list_things_at ( self , location , tclass = Thing ) : return [ thing for thing in self . things if thing . location == location and isinstance ( thing , tclass ) ]
Return all things exactly at a given location.
Return all things exactly at a given location .