input: Write a function to sum all the elements in the given list and return the sum. If the list is empty, return 0.
  
  def sum_list(lst):
      total = 0
      for num in lst:
          total += num
      return total
  
  assert sum_list([1, 2, 3, 4, 5]) == 15
  assert sum_list([0, -1, 1]) == 0
  assert sum_list([10, 20, 30]) == 60
  assert sum_list([-1, -2, -3, -4, -5]) == -15
  assert sum_list([]) == 0
output: def sum_list(lst):
      total = 0
      for num in lst:
          total += num
      return total