input: Write a function to suggest an improvement for the following Python code that calculates the sum of elements of a list. The provided function should replace the original code with a more efficient or concise implementation.
  
  
  def sum_elements(arr):
      sum_value = 0
      for num in arr:
          sum_value += num
      return sum_value
  
  
  assert sum_elements([1, 2, 3, 4, 5]) == 15
  assert sum_elements([]) == 0
  
  def sum_elements(arr):
      return sum(arr)  # return sum of elements of arr with one line of code.
  
output: def sum_elements(arr):
      return sum(arr)