input: Write a python function to remove duplicates from a list.
  assert compact_list([1, 2, 2, 3, 4, 4, 5]) == [1, 2, 3, 4, 5]
  assert compact_list([10, 20, 20, 30, 30, 30, 40]) == [10, 20, 30, 40]
  assert compact_list([5, 5, 5, 5, 5]) == [5]
  assert compact_list([]) == []
output: def compact_list(lst):
      return list(dict.fromkeys(lst))