input: Write a python function to sort an array using a class method.
  assert Sort().sort_arr([4, 2, 7, 1]) == [1, 2, 4, 7]
  assert Sort().sort_arr([10, 5, 8, 3]) == [3, 5, 8, 10]
  assert Sort().sort_arr([3, 3, 2, 1]) == [1, 2, 3, 3]
output: class Sort:
      def sort_arr(self, arr):
          return sorted(arr)