input: Write a function to calculate the total sum of all elements in the given list using a for loop. If the given list is empty, return 0.
  assert calculate_sum([1, 9, 3, 5])==18
  assert calculate_sum([10, 20, 30])==60
  assert calculate_sum([-1, 3, -5, 7])==4
  assert calculate_sum([0, 0, 0, 0])==0
  assert calculate_sum([])==0
output: def calculate_sum(lst):
      total = 0
      for num in lst:
          total += num
      return total