addThing :: Thing -> Package -> Package
addThing (index, weight, cost) (indices, totalWeight, price) =
    (index:indices, weight + totalWeight, cost + price)
addThing :: Thing -> Package -> Package
addThing (index, weight, cost) (indices, totalWeight, price) =
    (index:indices, weight + totalWeight, cost + price)
addThing (index, weight, cost) (indices, totalWeight, price) =
    (index:indices, weight + totalWeight, cost + price)