input: Write a python function to find the symmetric difference between two lists.
  assert symmetric_difference([1, 2, 3, 4], [2, 4, 6, 8]) == [1, 3, 6, 8]
  assert symmetric_difference([10, 20, 30], [30, 40, 50]) == [10, 20, 40, 50]
  assert symmetric_difference([1, 1, 2, 2], [2, 3, 4]) == [1, 3, 4]
output: def symmetric_difference(list1, list2):
      set1 = set(list1)
      set2 = set(list2)
      sym_diff = set1.symmetric_difference(set2)
      return sorted(list(sym_diff))