input: Write a python function to sort an array in ascending order.
  assert sort_array([5, 8, 1, 4, 9]) == [1, 4, 5, 8, 9]
  assert sort_array([10, 2, 3, 1]) == [1, 2, 3, 10]
  assert sort_array([20, 15, 30, 5]) == [5, 15, 20, 30]
output: def sort_array(arr):
      return sorted(arr)