input: Write a python function that accepts a list of integers and returns the total of the absolute values of those integers, multiplied by the product of their signs. If the list is empty, the function should return None.
  assert prod_signs([1, 2, 2, -4]) == -9
  assert prod_signs([0, 1]) == 0
  assert prod_signs([1, 1, 1, 2, 3, -1, 1]) == -10
  assert prod_signs([]) == None
  assert prod_signs([2, 4, 1, 2, -1, -1, 9]) == 20
  assert prod_signs([-1, 1, -1, 1]) == 4
  assert prod_signs([-1, 1, 1, 1]) == -4
  assert prod_signs([-1, 1, 1, 0]) == 0
output: def prod_signs(nums):
      if not nums:
          return None
      abs_total = sum(abs(x) for x in nums)
      sign_product = 1
      for num in nums:
          if num == 0:
              return 0
          sign_product *= 1 if num > 0 else -1
      return abs_total * sign_product