input: Write a python function to calculate the sum of all elements in a given list.
  assert sum_of_elements([1, 2, 3, 4, 5]) == 15
  assert sum_of_elements([10, 20, 30, 40]) == 100
  assert sum_of_elements([0, -1, -2, -3, -4]) == -10
output: def sum_of_elements(lst):
      return sum(lst)