input: Write a function to improve the given Python code for finding the sum of elements of a list. The improved code should be more concise and efficient.
  
  ### Input:
  def sum_elements(arr):
      sum_value = 0
      for num in arr:
          sum_value += num
      return sum_value
  
  ### Output:
  def sum_elements(arr):
      return sum(arr) # return sum of elements of arr with one line of code.
  
  assert sum_elements([1, 2, 3, 4, 5]) == 15
  assert sum_elements([-1, 0, 1]) == 0
  assert sum_elements([]) == 0
  assert sum_elements([10, 20, 30, 40]) == 100
  assert sum_elements([-5, -3, -1, 0, 1, 3, 5]) == 0
output: def sum_elements(arr):
      return sum(arr)