input: Write a function to find the sum of elements of a list. Use a more concise method to achieve the same result. If the list is empty, return 0.
  assert sum_elements([1, 2, 3, 4])==10
  assert sum_elements([0, -1, 1])==0
  assert sum_elements([])==0
output: def sum_elements(lst):
      return sum(lst)