input: Write a function to calculate the total sum of all elements of a given list. If the list is empty, return 0. Otherwise, iterate through each element in the list and accumulate the total sum.
  assert calculate_sum_of_list([1, 2, 3, 4])==10
  assert calculate_sum_of_list([5, 10, 15, 20])==50
  assert calculate_sum_of_list([0])==0
  assert calculate_sum_of_list([])==0
output: def calculate_sum_of_list(lst):
      if not lst:
          return 0
      return sum(lst)