input: Write a function to calculate the total sum of all elements in a given list. The function should iterate through the list, adding each element to a running total, and then return the final sum.
  assert calculate_total_sum([1, 9, 3, 5])==18
  assert calculate_total_sum([2, 4, 6, 8])==20
  assert calculate_total_sum([0])==0
  assert calculate_total_sum([])==0
output: def calculate_total_sum(lst):
      total = 0
      for num in lst:
          total += num
      return total