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