bool CanEat(Animal animal)
{
    if (animal.Is(WaterCreature))
    {
        if (animal.Has(Scales) OR animal.Has(Fins))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    else if (animal.Has(Wings))
    {
        if (animal.Is(Bird))
        {
            if (animal.Is(Scavenger) OR animal.Is(BirdOfPrey))
            {
                return false;
            }
            else
            {
                return true;
            }
        }
        else if (animal.Is(Insect))
        {
            if (animal.Walks<on>(AllFours) OR animal.Leaps<on>(JointedLegs))
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }
    else if (animal.Moves<on>(Ground))
    {
        if (animal.Has(DividedHooves) OR animal.Has(ClovenFeet) OR animal.Chews(Cud))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    throw new FoodRuleException("It's probably fine. See also Mark 7");
}