input: Write a python function to remove duplicates from a list.
  assert remove_duplicates([1, 2, 3, 4, 4, 4, 5])==[1, 2, 3, 4, 5]
  assert remove_duplicates([1, 1, 1, 1, 1, 1, 1])==[1]
  assert remove_duplicates([5, 6, 7, 8, 8, 9, 10, 10])==[5, 6, 7, 8, 9, 10]
  assert remove_duplicates([])==[]
  assert remove_duplicates([2, 3, 5, 7, 11, 13, 13, 13, 17])==[2, 3, 5, 7, 11, 13, 17]
output: def remove_duplicates(lst):
      return list(dict.fromkeys(lst))