input: Write a function to compute running sum.
  assert running_sum([1, 2, 3, 4, 5]) == [1, 3, 6, 10, 15]
  assert running_sum([10, 20, 30, 40, 50]) == [10, 30, 60, 100, 150]
  assert running_sum([0, -1, 1, -2, 2]) == [0, -1, 0, -2, 0]
output: def running_sum(nums):
      result = []
      current_sum = 0
      for num in nums:
          current_sum += num
          result.append(current_sum)
      return result