Exercise: running totals

Write a function running_totals(nums) that returns a new list of running totals: each of its elements is the sum of the elements of nums from the start through the same position inclusive. The function does not change the list nums itself.

• running_totals([1, 2, 3]) → [1, 3, 6]
• running_totals([3, -1, -2]) → [3, 2, 0]
• running_totals([]) → []

Constraints: nums holds from 0 to 1000 integers from -1000000 to 1000000, negative ones included; for an empty list the result is an empty list; after the call, nums holds the same elements in the same order.

Do not add extra imports unless the task says so explicitly.