Function arraySum

Calculates the sum of all elements in the array based on the provided function.

arraySum<T>(arr, fn): number
Type Parameters
- T
Parameters
- arr: T[]
  Array of items to be summed.
- fn: ((item: T) => number)
  Summing function
  - - (item): number
    - Parameters
      item: T
      Returns number
Returns number
Examples
```
const total = arraySum([1, 2, 3, 4, 5], (num) => num);

console.log(total); // 15
```
- Defined in utils/array-sum.ts:15