rooms = {
    "hall": "Candles float. Long tables groan with food.",
    "yard": "Cold grass. The Whomping Willow creaks.",
    "tower": "Spiral stairs. Owls hoot above."
}

def enter(room_key):
    description = rooms.get(room_key, "You are lost in mist.")
    print(description)

enter("hall")
enter("dungeon")   # not in dict — uses default message