input: Write a function to improve the efficiency of calculating the sum of elements in a list by using a built-in function. If the given list is empty, return 0.
  assert sum_elements([1, 2, 3, 4]) == 10
  assert sum_elements([-1, -2, 3, 4]) == 4
  assert sum_elements([0, 0, 0, 0]) == 0
  assert sum_elements([]) == 0
output: def sum_elements(lst):
      return sum(lst) if lst else 0