input: Write a python function to remove duplicate elements from a list.
  assert remove_duplicates([1, 2, 3, 1, 2, 4, 5, 6, 5]) == [1, 2, 3, 4, 5, 6]
  assert remove_duplicates([7, 8, 9, 7, 9, 10, 10]) == [7, 8, 9, 10]
  assert remove_duplicates([11, 12, 13, 11, 12, 14]) == [11, 12, 13, 14]
output: def remove_duplicates(lst):
      return list(dict.fromkeys(lst))