Running Total

A running total adds numbers up as it goes and notes the sum after each one, the way a bank statement shows the balance after every payment. Write running_total(nums) that returns a new list where each item is the sum of all the numbers up to and including that position.

An empty list gives an empty list.

Examples

running_total([1, 2, 3, 4])      # returns [1, 3, 6, 10]
running_total([5, -2, 7])        # returns [5, 3, 10]
running_total([8000, 0, 12000])  # returns [8000, 8000, 20000]

In the first example the totals are 1, then 1 + 2, then 1 + 2 + 3, then 1 + 2 + 3 + 4.