input: Write a python function to calculate the sum of the elements in a list.
  assert sum_elements([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == 55
  assert sum_elements([10, 20, 30, 40]) == 100
  assert sum_elements([5, 5, 5, 5, 5]) == 25
output: def sum_elements(lst):
      return sum(lst)