input: Write a function to improve the efficiency of the given function for finding the sum of elements of a list by replacing it with a more efficient solution. Return the sum of elements of the list directly using built-in functions.
  
  
  def sum_elements(arr):
      return sum(arr) # return sum of elements of arr with one line of code.
  
  # Test cases
  assert sum_elements([1, 2, 3, 4, 5]) == 15
  assert sum_elements([-1, -2, -3, -4, -5]) == -15
  assert sum_elements([]) == 0
  assert sum_elements([10, 20, 30]) == 60
  assert sum_elements([1.5, 2.5, 3.5]) == 7.5
  
output: def sum_elements(arr):
      return sum(arr)