input: Write a function to sort an array in ascending order.
  assert sort_asc([5, 3, 7, 1, 9]) == [1, 3, 5, 7, 9]
  assert sort_asc([10, 2, 33, 21, 5]) == [2, 5, 10, 21, 33]
  assert sort_asc([3, 1, 2]) == [1, 2, 3]
output: def sort_asc(arr):
      return sorted(arr)