in the first lastStoneWeight, `proc lastStoneWeight(stones: var Stones): int`, it requires a var.
`var stones = weights.mapIt(Stone(weight: it)).toHeapQueue` makes a var or a variable to a mutable value, okay, and you pass it. `result = lastStoneWeight(stones)` but here, `lastStoneWeight(weights.mapIt(Stone(weight: it)).toHeapQueue)`, there is no var being made, and you pass it an immutable value.
