input: Write a function to sort an array with m different types of elements.
  assert sort_array([2, 1, 1, 3, 6, 4, 5, 5]) == [1, 1, 2, 3, 4, 5, 5, 6]
  assert sort_array([4, 3, 1, 2, 2, 3, 1]) == [1, 1, 2, 2, 3, 3, 4]
  assert sort_array([5, 4, 4, 3, 2, 5, 1]) == [1, 2, 3, 4, 4, 5, 5]
output: def sort_array(arr):
      return sorted(arr)