input: Write a python function to remove duplicates from a list.
  assert remove_duplicates([1, 8, 10, 4, 1, 8, 8]) == [1, 8, 10, 4]
  assert remove_duplicates([5, 3, 3, 2, 1, 1]) == [5, 3, 2, 1]
  assert remove_duplicates([7, 7, 7, 7, 7]) == [7]
output: def remove_duplicates(lst):
      return list(dict.fromkeys(lst))