Define a function vip_ratio that consumes a MonsterMash (!!) and produces a float by dividing the number of Monster in the monsters list (the VIP monsters) by the number of monsters attending (the head_count in the party field). If the head_count is 0, then return 0.0 instead.

The file monster_mash.py is in monster_mash.py and in the monster_mash.py tab of the sandbox (To sandbox).