input: Write a python function to remove duplicates from a list.
  assert remove_duplicates([1, 2, 3, 4, 4, 5, 1])==[1, 2, 3, 4, 5]
  assert remove_duplicates([10, 20, 20, 30, 40, 40, 50])==[10, 20, 30, 40, 50]
  assert remove_duplicates(['a', 'b', 'b', 'c', 'a'])==['a', 'b', 'c']
output: def remove_duplicates(lst):
      return list(dict.fromkeys(lst))