input: Write a function to sort an array in ascending order.
  assert sort_array([3, 1, 2, 5, 4]) == [1, 2, 3, 4, 5]
  assert sort_array([10, 3, 15, 7, 8]) == [3, 7, 8, 10, 15]
  assert sort_array([2, 2, 2, 2, 2]) == [2, 2, 2, 2, 2]
output: def sort_array(arr):
      return sorted(arr)